Yeah... Because massive companies use them anti-competitively as a moat against other companies, and as a loss leader to enable massive data collection and vendor lock in.
"browsers aren't really a self funding product" is a symptom of dysfunction, not the inevitable conclusion of a fair market.
The synergistic effects are so strong that most users would prefer there to be The System, in which everything works together and there's no risk of incompatible choices. They don't necessarily care which system.
The market in things like, say, file explorers is tiny. There's a few shell replacements (free), Midnight Commander and clones, and maybe over in the corner someone making a few thousand dollars a year from an Explorer replacement.
There are probably plenty of such examples.