Comment by jsheard

> Firefox and Chrome also use C++, and each of them has 3-4 critical vulnerabilities related to memory safety per year, despite the massive resources Mozilla and Google have invested in security.

And part of Firefox/Chromes security effort has been to use memory safe languages in critical sections like file format decoders. They're far too deeply invested in C++ to move away entirely in our lifetimes, but they are taking advantage of other languages where they feasibly can, so to write a new browser in pure C++ is a regression from what the big players are already doing.