Content shifting around is right up there with pop-up ads in terms of user frustration.
I disagree, especially with the almost complete absence of any progress bars or loading indicators that the UI designers seem to love so much and have forced newer browsers to have. "Something happening" on the page is nice way to know that it is still loading. A white screen is worse.
(Then again, I'm used to pre-Webkit Opera, which has a very prominent progress bar and applies CSS as it loads.)
Avoid specifity in CSS by adding bits of complexity in your HTML markup. Your style sheet foot print will be so small you'll never need any of these tricky patterns.
I appreciate these efforts to optimize load times, but the problem we see today slowing down the web is caused by designers making 2MB+ webpages for simple articles you could deliver in 20KB. Why can't we stop it from the source and just decrease webpage garbage? In that case, CSS is negligible adds only milliseconds to the total load time.
Garbage attracts the masses. Advertising pays the bills. The unnecessary crap that we developers would blow away are, unfortunately, the only thing that the laity come online for and therefore the only reason why we have jobs/customers.
Better we explore techniques to optimise, no matter how incremental, so that we can shave as many milliseconds as possible without compromising on the nectar of content and thus challenge native app experiences on mobile devices.
Kudos for chrome giving a nod to MS edge, and to the edge team for making things cool.