So system warring in the hobby has taken a weird turn since the whole WotC debacle. I shared two different posts kind of touching on the subject, that I agree with in some manner or the other.
Let me lay it out for you:
No one should be shamed for their preferred system. This hobby is about fun & games and people should be allowed to enjoy what they enjoy. If you only wanna play 5e, fine. If you'd rather play anything else, also fine. If you're shaming people for their preferred system you're doing more harm than good.
A little homebrew here or there also does not mean someone needs to play something else instead. Everyone has house rules.
However, treating 5e like it's a universal system that can run any genre of game is insane.
There are literally thousands of games out there that already do what your homebrew D&D 5e conversion would do and more, save yourself the energy and just play that.
Additionally, Most systems you could play as an alternative to D&D are way cheaper, if not free in comparison to the massive tomes WotC puts out each year. Many of them are just as supported if not more so by their creators in the form of digital tools and add ons too.
If you are affording new purchase of 5e books on the regular, you can absolutely afford to branch out into other cheaper systems. A dogmatic devotion to D&D is what contributes to WotC's stranglehold of the market share.
This fear of learning new systems in the hobby is bad for players, bad for GMs, and bad for the hobby's health. If you've genuinely tried other systems and still prefer 5e, Great! Have fun!
If you're a person who wants to play a genre conversion for D&D (think Pokemon D&D! One Piece D&D! Fallout D&D!) - I recommend you grab one of the numerous games specifically designed to capture that genre rather than putting a D&D square peg in a round fallout hole.
If you're a player in this scenario, then shame on you for demanding your DM go through the hard work of converting an entire genre into 5e just so you don't have to learn a new system.
Some of my favorite mechanics and favorite sessions at the table have come from sessions of Pokemon Tabletop Adventures, Call of Cthulhu, City of Mist, Pathfinder 1e, etc. I've even carried minor game design back into my 5e games to make them better too. There is space for both. 5e Players and Other System Players are brothers and sisters in gaming, and we should be uplifting and challenging each other - not fighting and demeaning each other.
5e players aren't stupid, and you're not some leet gamer because you play Pathfinder or GURPS instead. 5e also isn't God's gift to gaming.
Expand your horizons, but enjoy what you like. Catch flies with honey not vinegar. Telling people they have BRAIN DAMAGE FOR ENJOYING 5E is beyond the pale and insisting there's NO POSSIBLE WAY I COULD EEEEEEVER learn a new system is just laziness to the point of idiocy.