> faster first meaningful content paints.

That seems like trying to address one of the symptoms, not the underlying problem. "First meaningful paint" means nothing to me, depending on what the developer means by "meaningful". Why can't I just have the whole page load and display quickly?

A lot of this nonsense is because of mobiles. Mobile browsers don't handle some UI elements (checkboxes, radios, drop-downs) very well, and all the browsers have "interesting" incompatibilities; so developers use these compatibility shims, which usually result in a badly-degraded desktop experience, and slowness for everyone.

So I'm blaming the mobile browsers. They don't deal with standard markup properly.