Regarding your post(s) about investigation checks and the like, there's something that's bothering me, and it bothered me for a while. Not in regard to investigation, but charisma (and similar checks, diplomacy, negotiation, persuasion, whatever the game calls it).
In a TTRPG with skills, those skills are an abstraction meant to simulate a characters actual capabilities. If I want to make a character who can effortlessly jump from rooftop to rooftop, I'll give them high Athletics, Agility, Endurance, whatever. Maybe some feats, abilities, perks, advantages etc that pertain to jumping. Now, if I want my character to jump from rooftop to rooftop, I just roll the dice, and the skills, attributes, perks etc will make sure I have a high likelihood of success. I don't need to prove to the GM or the group that I myself could make that jump.
But now let's talk about Charisma checks. I've often heard stories of groups who say they don't make those checks, they just let the player make the argument, and if the GM is convinced, they "pass." But like... that means the character will always be as persuasive as the player. If the player isn't good at formulating an argument, the character won't be, either. Same with perception, investigation, etc. Sometimes, players just aren't good at picking up on hints and clues and/or they're not good at drawing conclusions from the clues they have. So that means that they can't play as a character who is?
Don't get me wrong, I get your point, I just find this is an issue worth thinking about. Why are things like athleticism, stealth, and combat prowess, or even things like lockpicking, hacking, or repairing stuff okay to abstract away as dice rolls, but deduction, perception, and maybe also persuasion and rhetoric aren't? Or, maybe the better, more constructive question: How would you propose handling a player playing a character whose skills exceed the player's?
I also think it's an issue worth thinking about, but I think "thinking about it" also has to involve asking the questions "why is this a problem?" and "is this ACTUALLY a problem?"
Like this discussion comes with the prepackaged assumption that allowing you to play a character whose abilities exceed yours as a player is both a) a universally desirable thing, and b) something that must be treated as a game design priority. And, with that assumption, it's logical to conclude that a TTRPG has an *obligation* to allow you to play a character whose abilities are not limited by yours as a player in any way, and not allowing you to do so constitutes a failure on the game's part.
But let's question that assumption a little bit. Because, the way I see it "allowing you to play a character who is good at X even if that's something that you, personally, are not good at" is not an inherently desirable design goal. It's a value-neutral feature, and it becomes a good or bad design goal to pursue depending on what X is and whether abstracting X so that the player doesn't have to engage with it benefits or detracts from the desired gameplay experience.
Let's for example, imagine a TTRPG with wargame elements, where, among other things to do, there are situations where your character can assume command of an army to engage in large-scale battles. It's pretty clear that, in such a game, you simply can't play as a character who is a better tactician than you, the player, are. If I'm not a good tactician, I don't get to play a character who's supposed to be the most brilliant tactician in all the land. That's simply not a character concept I get to play unless I am also skilled at tactical decision-making.
Is that inherently a problem to be solved? If we got rid of tactical decision-making as an activity that the players have to engage in, and instead gave the characters a "Tactics" skill and we used a Tactics skill check to determine whether they win or lose a battle, that would certainly allow a player who's bad at tactics the freedom to play a character who's the best tactician ever. But would this be an objectively good change? I'd say no, because it would skip past the entire point of the wargame elements, which is engaging as a player with the process of tactical decision-making, and that's not something that I'd consider worth sacrificing in pursuit of allowing the player to play a character whose skills exceed theirs in this particular aspect.
To name a more concrete example that someone else mentioned in the notes of that post: Mothership has no equivalent of a stealth skill, despite being a game where a lot of your playtime is spent hiding from some flavor of Scary Space Monster, because if the game abstracted stealth that way the resolution to any situation where you're trying to hide from a Scary Space Monster would be saying "I roll stealth" and hoping you roll high enough. Without a stealth skill, you're forced to participate in the narrative conversation of paying attention to the GM's description of the environment, ask clarifying questions if needed, and describe how you try to hide in the space presented to you.
This, once again, presents a situation where your character's skills are limited by your own. It's pretty clear that your character can only be as good at hiding as you are at thinking of places to hide and describing how they hide in them, and that if the game took the "i roll stealth" approach instead, it would solve the "problem" of your character's skills being limited by your own in this particular way. But is solving this "problem" worth sacrificing the tension that the game seeks to create by deliberately refusing to abstract stealth in this way?
So yeah... I think lacking skill checks for stuff such as perception or investigation makes a dungeon-crawling game better because it forces the players to narratively engage with the environment as a real place when they're looking for something, and it's also true that the lack of such mechanics kinda does mean that a player who just isn't good at picking up hints and clues from environmental details simply doesn't get to play a character who is supposed to be good at picking up hints and clues from environmental details. But I think that ensuring a player's ability to play such a character regardless of their real-life skill level is not a design goal that a game has any inherent obligation to pursue, especially not at the cost of skipping over the actions that, to me, are the meat and potatoes of a dungeon crawl.
My answer to "why is it okay to abstract certain skills as dice rolls and not others" is that games are allowed to make decisions about which actions they want to skip over with a dice roll and which actions they want the players to have to exercise direct narrative control and mastery of, and sometimes that's gonna interfere with their freedom to play a character whose skills exceed theirs, and that's okay because sometimes other game design goals are going to have priority over the goal of ensuring the character's skills aren't limited by the player's real-life skills in any conceivable way.