Many of the things I'm talking about aren't even debatable they are simply bugs. For example infinite scrolling areas jumping around as they load content and the interface having variable and high latency in response to user input. 'Poor reimplementations' could be stuff like copy and paste being bugged out in a text box.
In any case you're right, I think there isn't enough study into these things.
Maybe there's some abstract notion of "good UI" that is distinct from "people like to use it". Or maybe people are stupid.
But on a purely empirical basis there is absolutely no evidence for the supremacy of the old UI paradigms you champion.