But they are. There’s absolutely no question about that. A browser will only render in the absence of a stylesheet if a) there’s programmatic intervention from the developers (e.g. timeouts) or b) if the server ultimately responded with a TCP timeout because of an outage. In the latter case, rendering is blocked for 20s on Win and 80s on *nix. CSS is render-blocking. There are no two ways about it. You can verify either slowdowns or outages by using https://slowfil.es or a blackhole server respectively.

> If you control your layout with JavaScript, things like orientation changes can take a short time to update after the viewport has altered. It’s not ideal, but it’s not awful either.

In this scenario you’re CPU-bound and not network-bound. Dispatching render-blocking requests on a high-latency connection JIT is far worse than front-loading your CSS asynchronously with minimal priority.

> I disagree with your second claim. I assert (without statistics) that the chance that a print stylesheet will be needed are more than a million to one against

I agree that print stylesheets are very very very rarely needed. My point—which I stated already—is that to accommodate individual media types increases complexity in the browser for zero gains.