In what way is this gatekeeping? The working class can quite easily understand that we are being exploited, just looking at disparity alone makes it come quite easily to us. However, the inner workings of capitalism, imperialism, its drives, how it works and functions, all of this is far from obvious. If it were truly obvious, then everyone would probably already be a Marxist.

I can say that revolutionaries should be trained, because we know what happens when they are, vs. when they aren't. For example, in the Russian revolutions, many factions tried to rely on "sponteniety" or otherwise disapproved of revolutionary theory. These factions all lost out to the bolsheviks, who were dedicated, professional revolutionaries.

That isn't to say that the entire working class shouldn't participate, just that they won't be the ones leading revolution. Lady Izdihar made a helpful diagram:

All of these components are necessary for success, which we can verify by looking at successful vs. failed revolutions. It isn't gatekeeping to say that a random person should be a surgeon without due training, but instead aconowledgement that for success, we need to train, and that we cannot expect everyone to have the time and dedication to train equally. This isn't shutting people out of the movement, but proper organizing.