The problem is the complexity of all the specifications that make up the Web. These specifications are heavily influenced by whatever major browsers already are doing (i.e. influenced by a handful of huge tech companies). These companies have a vested interest in making it hard to make a new, competitive browser.

I think the Web is unredeemable at this point; there is so much entrenched complexity, ugly hacks, centralization, and misuse of various technologies that it can never be undone. The only solution is to refuse to contribute to the Web at all, which is hardly an option for most of us here.