Serious question: if you're building an application, why do you want this? It used to be a huge thing to build Apple, Windows, Motif, whatever apps closely in accordance with their interface guidelines and idioms, but for some reason on the web everyone seems to need an idiosyncratic, opinionated set of basic controls.
I agree with you and I am sure I am not saying anything new, but the fact that on the web content, presentation and marketing sites heavily outnumber webapps, and that one needed to stand out - even if superficially - from countless other options, caused a much larger emphasis being put on customizability, looks and originality which didn't stop at layouts colors and typography, but seeped into interactions. So a lot of jobs got created, lots of users suffered from slow, confusing and buggy UI/UX but at least lots of originality and prettiness was had :)
Oh for sure if there was a web platform look, I would happily oblige and use that look. The point is that there isn't one so in that case I would rather have something different.
If we had gone down the path of smart documents instead of web apps for the internet, we would have had a better time for sure.
