While I haven't really been able to deploy it as of late, since most games I run are either one-shots or running simpler systems, communal rules-learning has been a huge boon for GMs that is rarely brought up to help tackle moderate-to-heavy systems.
With the GM-Player dynamic often being framed as "Person That Knows Rules" v. "Person That Relies on the Person That Knows Rules", it places all of the weight of knowledge and responsibility onto the GM and allows a Player to only ever have to remember exactly what they have to use. No further effort within the group nor engagement with the system. Almost like a video game wherein you plug your actions in and everything else is done for you.
Communal rules learning leans very well into more weighty systems, where players will have to know more than just the base concepts of rolling dice and adding modifiers. Either as a part of Session Zero, or prior to Session Zero if you can, you can assign a section of a book to each player to read through and do a quick write-up of how that section operates.
Many hands make light work and it means that the GM, who still does need to have done some reading of all sections, has at least one other person at the table to help them along.
For example, @nerdyogre ran Mage: the Awakening 2nd many years ago and had each of the four of us handle a different chapter. One of us did Combat, another did Spellcasting, and the result was much smoother when we could point to each other and go "so how does this work" and get a quick and usually accurate answer.
It definitely took a load off when you didn't have to be the sole source of rules explanations. (Unfortunately replaced by 4 jackasses with wizard powers, but hey that's Mage)
I remember games of Anima: Beyond Fantasy where I was playing a Ki user and had to learn how those mechanics worked. Same for Shadowrun 5th, especially in regards to hacking, if you were playing the decker you needed to know what was up with that subsystem.
A mate and myself are both diving into Ars Magica 5th and already know that it's going to be the only reasonable way to get a group around the game.
