The PBE is really just for bug testing

I know some people like to say that so lets pretend that's true. So wtf is this "data gathering" riot does? I know they love to throw changes onto the PBE for a day or too then just magically take them off and go, yep, tested, needs more testing. What testing? You know the PBE environment is a joke right? You have to, you have to be retarded to not know PBE is a joke. So what kind of data exactly are you extracting from the PBE and how can it be possibly relevant to the health of the game when, again, the PBE environment is a joke. Or do you have your own private riot clubs where you gather the 4 people that work there and just have them 1vs1 and when the vayne player gets raped you go, yep, botrk is fine right now?

I don't get, explain it to me.