Question about overview

Is there a reason that they made the game in such a way where you can't see what items your opponent is using beforehand? In VGC can they not see what items their competitors have? Maybe they just know because they take notes during the rounds or whatever, but it feels kinda crummy that I have to guess whether my opponent has a focus sash, choice scarf, weakening berry. Is there some reason they don't have it in the overview at the beginning? Would it break the meta or something? I'm just frustrated because there's already so many other things to consider with weather, speed tricks, entry hazards, intimidates, and now I have to guess their items too? Maybe I'm just old but it is a lot to consider and I'm not trying to have a notepad or a damage calculator open while I play. I just wanna play and not be completely blindsided by something I never even considered