the Queens Gambit Accepted

I should mention another reason why the QGA is less popular than the Slav or the QGD. 

After 1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. e3 e6 5. Bxc4 c5 6. 0-0 a6, white has about ten good moves. None of them put black in any serious danger but black has to do a wide range of work. Even 7. e4 exists. All kinds of random stuff that’s semi-serious. Point being, the way black has played is not super forcing and so you can call this a practical inconvenience for the human player.

To be fair, there are some sharper alternatives black can play here and there, on move four for example. I’m fond of some of them, definitely good enough for a human master or even GM. But some of those lines may give white more chances of achieving something serious than the super-main-line I mentioned above.

Food for thought anyway. Def a big chapter of opening theory no matter how you slice it. But then again what isn’t

if someone can learn ALL the theory stemming from simply playing 1.e4,... then 10 moves inside a specific structure doesn't seem undoable. I've been looking at some games.