They are, see how both Safari and Firefox, the 2nd and 3rd most popular browsers, have brought in tens of billions of revenue per year. Safari is immensely profitable, Firefox too would be if Mozilla wouldn't be run in an absurdly poor manner.
> the user gains a huge amount of value by a browser being integrated into the OS, webviews in other applications, etc
What is the huge value gain that e.g. Safari being integrated into MacOS is bringing me? Why couldn't webviews be backed by a browser of my choice?