I disagree that this is a useful definition of gatekeeping. Gatekeeping is, simply put, the erection of artificial barriers to entry. This may be intentional, which is often seen as more egregious if based on extraneous or unnecessary criteria, but it can also be unintentional. If you require intentionality, you're going to miss a lot of structural and systemic gatekeeping that grows up not through intentional action, but emergent or unforeseen consequences of non-intentional actions that combine to create artificial barriers to entry.
And, the "hard" in GMing is largely systemic, now. It's the accretion of expectation that's been built up around what being a GM is. Here's an example: a three room dungeon with 3 encounters with 2 goblins each is a D&D game. It has no fancy bells, no whistles, it's straightforward, and requires very little to GM. The problem is that, immediately, the response will be all about how this wouldn't satisfy "my" table, or there's more you could do, or that's too simple. IE, we're going to add our expectations for a game onto the definition of what it means to GM. We're going to erect artificial barriers to entry through increased expectation of work on the part of the GM, and then codify that as the actual job of the GM. We're erecting barriers based on the aggregate of both 35+ years of the hobby and our combined personal expectations of what a game looks like. But, that's not actually part of the necessary tasks of being a GM. I can be a GM at a much lower level of output. So, if we're going to classify GMing as "hard" and name the GM as the "most important" person at the table do to the expectations we've assigned, we've created an artificial barrier to entry to being a GM. And, that's gatekeeping. Not intentionally -- we're all acting in ways we deem to be reasonable and not intentionally keeping people out -- but still in a way that restricts the membership into the GM club. Even if you welcome a neophyte GM, if your mentorship is showing them all the hard work they'll have to do, you're gatekeeping even though it's wearing the guise of being helpful.
To take some examples from responses to me, it's been said that adjudicating actions is harder than declaring them. But, most of the list are almost always trivial -- and should have been part of the player's job to make sure remain trivial because the player has the duty to engage with the fiction. The "hardest" parts of the job are picking a DC, which, again, if you use the DMG advice, is a question of "is this task easy, moderate, or hard?" This isn't hard. The numerated list presented mostly trivial steps in an attempt to make the process look more complicated that it actually is, in practice. I think a lot of that list comes from the unstated belief that it's the GM's job to police the players -- that the players will not be acting in a disciplined fashion and will present action declarations that require extra work on the GM's part to vet and untangle from abuse. But, that's a player problem, not a GM duty.
And, having to be the one that knows the rules best at the table is also part of the assumption that it's the GM's job to police players. You need to know the rules so that you can make sure the players follow them properly. But, that's a player problem, again, not a GM required duty. I, personally, have a cleric in the group I run for and I couldn't tell you at all how Turn Undead works, or what things that PC has that might interact with that. I know she can Turn Undead, but that's it, and I really don't think about it at all. If it comes up in a session, like it did a few months ago, I'm often surprised, because I forgot about it. My player knows her rules, and follows them, and I don't have to think about it at all. If a question comes up, I'll tell the player to read the rule and report back while I move on to other things. OR, I'll make a ruling, and we'll address it later. I don't need to know these rules to run a game -- those rules are player facing, it's their job to know them and apply them through their action declarations. I'm there to frame the scenes and adjudicate the actions. Those rules I know very well. Luckily for me, even in 5e, they're pretty straightforward.
The worst part of running D&D is running the monsters, especially if they have a ton of special abilities. But, again, as GM, I pick the monsters, so that's entirely under my control as GM as to how much difficulty I add to myself. Same with campaign design, or adventure design. I pick my workload. If I ever feel like my players are dictating my workload, it's time to have a serious discussion with the group. If players are just there to do the minimum effort show up and toss dice and be taught/led through the rules by me, or constantly declare actions that require my vetting, we have a problem, and it's not that GMing is hard.
Part of the issue in this thread is the assumption that players have very little responsibility to the game and that it's the GM's job to compensate for this. Nope. That's on you if your take that burden up, it's not a task inherent to GMing.
