[sho_hn]

I've worked a bit on browser engines, although it was quite some time ago.

I don't think it'd help much.

- There's been a Cambrian Explosion in the web API surface era. The modern stuff dwarfs the old stuff. Dropping support for older/less frequently used mechanisms does not shed as much code and complexity as you might think.

- Beyond mere surface area, the level of engineering required to implement a sort of "Restricted Core Profile" to a competitive degree (e.g. performance) is quite high, if you're talking true blank-canvas development.

- There's a long tail effect in full force, where even mostly-modern websites will use and rely on some cruft here and there, making very few pages work in your supposed browser.

That is to say, it's still a very large, tough project. But the FOSS community has achieved quite a few large, tough projects; it's not the same as saying that it's not possible, of course.