Did the vayne buff make her like super strong or something?

She wasn't weak in the hands of people who are good with her before and it just made her just a peg easier. When you have a hyper scaling champ who can reliably do well early it never ends well.

She just got a chain of buffs and people wanna play her, thats all.

EDIT: don't understand down voting him for asking a question.

Vayne is like a cockroach a lot of players want to play her because she feels awesome when (if) she gets going. They don't do it just because they think she is weak. The buffs just gave them a reason.