Can we test ACTUAL changes on the PBE?

Why does it seem like Riot want to only do very small/irrelevant changes on the PBE, which they've pretty much already committed to releasing (i.e. plants, cho changes)

Why don't we try some actual changes on the PBE just to see how they fare. Like its the PBE after all, might as well try something new and see how it plays out in season 7?

Like maybe: try malzahar revert on PBE, just to see how it goes. You don't HAVE to put it in live, but c'mon, why aren't we at least TESTING it in the context of season 7.

Maybe: Try old last whisperer? It would make ADCs relevant mid-game again but not make tanks useless late game (45% bonus shred + 15% damg is ridiculous late, while 35% total shred is nice at ALL stages of the game). Maybe TRY making it a ranged-only item so assassins can't abuse it?

Maybe: If we change LW to range only, try making lethality melee-only and see how that fares? That way adc-dps is more prevalent whilst assassin burst is there.

Remember, these are suggestions that might be the stupidest shit ever and break the game in 17 different ways, but can we at least TEST these?

Maybe these changes will suck majorly and you can just not release them, but why aren't we AT LEAST testing something drastic to stop this shit-show meta. I mean, its the PBE after all...