Ask HN: Why has no-one fixed the problem of web elements moving as things load?

This is probably my pet peeve: Going to a website and trying to read some text, or maybe clicking on a button or even just seeing elements move around on their own as things load in. I try to click on a button and have it whisked away in front of my eyes and a new unrelated action occurs...

Why is this still a problem? With the website community still so stringent on standards and acessability why does this still happen on such prominent sites as youtube, facebook, google search etc. Is it just because the problem is hard to solve? Or is it just that there's market research or something that determines it's better to have some elements load early even if it results in bad practise?