Why is it just recently that people started to cry about Vayne?

Because she's been like this since FOREVER. The IE shiv build has always been there - people were just too dumb and went with bork instead. Vayne's problems did not start with the Q buff, she was too strong even pre-buff. Her early game hasn't been weak since forever either. Even if her early game was weak (which it isn't), it doesn't justify the kind of late-game monstrosity she becomes after the 30 minute mark. Kind of makes an 800 stack Nasus look weak.

Vayne's kit is inherently too strong. You can't have those ridiculously strong AAs two-shotting squshies as well as killing tanks in a couple of hits. A lot of people also don't get that her chase mechanics are a problem. It's simply impossible to escape an ulted Vayne reappearing across the other side of the map in a second's stealth.

In fact, I don't understand why an ADC even has true damage in the current state of the game. ADCs already deletes tanks so easily it's sad, why does Vayne need true damage on top of it?