To play devils advocate, Firefox breaks the monoculture, and arguably (Mobile) Safari too. If neither of these is big enough, will Ladybird be? I can’t imagine it getting bigger than them.
Not really as long as it is funded by Google.
If it’s not about tech but rather about funding, then should we be concerned of the monoculture of American browser vendors, or English speaking browser vendors? I don’t think we need to be, but I also think the tech side is the important place to prevent a monoculture for the open development of web technologies.
Not entirely separate anymore as both make use of shared external libraries.