When he talks about gameplay abilities at 16:17 he mentions
it may not work for your particular game, maybe you’re shipping a game with 200 plus enemies on screen, millions of projectiles tens or you know even hundreds of players
Can someone point me in a direction to understand why GAS is bad for many enemies?
Because it does a lot of calculations per single bot. And its same reason why we have blackboards, and state trees. Those require less code and are faster than doing it all in blueprints. And generally doing more than around 200 bots/players requires well optimized code. Unreal was made for games like quake and unreal with max of players around 60-100 (and those goals/numbers) are still there, like most of code is optimized with that number in mind.