The hypocrisy of the balance team

Why does the balance team say one thing for X but then does the opposite for Y?

For example, spellvamp was removed because it's hard to balance, but it was added to Rhaast's passive and scales higher than Will of the Ancients did?

Rengar was nerfed because it wasn't fair that he instantly bursts you from stealth (with a warning indicator) but Twitch can do it from more than 3x the range? Rengar's ult told you if you were even in the POSSIBLE area of his ult, and then warned you when you were the closest one. Twitch? Yeah you can see him for a second when he's too close.

Nidalee had her old Q reworked because it wasn't fair that she could spam it and chunk you with the lucky hit. Zoe Q can deal more, and you can't stand behind minions because it has an aoe splash.

They basically reverted the Jinx nerf that was done after her release because she was hitting a huge spike way too early, and nothing of it was nerfed slightly.

Why is this balance team always doing this? Is anyone expecting them to make any decent changes anymore? Honestly I'm more shocked when they make a good choice.