

Seems like your really pondering “HTML should be conspicuously slow for such a widely-used standard,” right?
The answer is that modern browsers are complex and highly optimized rendering engines.
Read back through this blog: https://mozillagfx.wordpress.com/
But in a nutshell, there’s a lot of talk about how modern browser are analogous to tuned game engines, heavily relying on the GPU and all sorts of hacks to render HTML efficiently. “Compiler” doesn’t even begin to do them justice, and modern GPUs are a core part of getting a good browsing experience.
V8 is another good example, taking what was a notoriously slow language (JavaScript) and hacking out a fast JIT engine for it.
The “standard” is ostensibly the HTML spec and such, but in reality whatever Chrome (and Firefox/Safari) renders is the standard. Devs build around their strengths and quirks, basically, instead of the other way around.
TBH 2-3 would be good, since each browser takes a monumental amount of effort/money to optimize and maintain.
Like, my best case somewhat plausible scenario would be Apple (and maybe some other vested interests?) merging Firefox and Safari into one open source effort that can keep up with Google (with Safari being a “branded” Firefox). There just isn’t enough money for a couple of open efforts to keep up with Chromium.