Yet, the web has been prospering for two decades in spite of the quasi-monopoly state of browsers. It's the living evidence that the dominant browser vendor doesn't has as much power as people imagine.
Like 90%+ of internet traffic goes to a handful of sites owned by tech giants. Most of what's left is SEO garbage serving those same tech giants' ad networks.
But walled gardens like YouTube, Discord, ChatGPT and suchlike that are delivered via the browser are prospering. And as a cross platform GUI system, html is astonishingly popular.
I’m sure you can come up with more examples of extremely high value business which would not have happened without the web.