At the time of Chrome's introduction, Firefox still had XUL extensions and a somewhat different UI from Chrome, so Chrome wasn't strictly superior (though it is fair to say it had better performance than Firefox). Over time, Mozilla replaced XUL extensions with Chrome's extensions API (without providing meaningful additions, like reintroducing the ability to modify the UI) and reworked the UI to be a clone of Chrome, so thanks to Mozilla's efforts it might be fair to say that today Chrome is strictly superior (excluding privacy and MV3 etc.).
(I still begrudgingly use Firefox BTW :))
I can't speak to the technical capabilities early on, but I will say that I distinctly remember many of the computing people I knew explicitly not preferring Chrome early on. I distinctly remember a discussion in one of my college CS courses, shortly after the release of Chrome, where everyone was in agreement that Chrome was just "that awful browser that Google made".
Yes, Chrome was absolutely superior to Firefox in every way at the beginning.
> impossible for new entrants unless they invest billions
All industries require that you invest billions, and it’s to compensate the civilization-long effort of R&D that the other company did. Reasoning-by-absurd: Should Boeing display all the plans of the band new Dreamliner so that it doesn’t take billions for new competitors to emerge? Should all companies make their blueprint public so they can have immediate competition? No, Google invested in browsers and set up new norms in WWW in exchange for their position on the market. The benefit to the general population has been excellent WWW norms, to be honest.
I’m thinking outside the law framework but to me, no corporation should be have 51% market share. But that’s wishful thinking, not the law (also, market share is something economists struggle to define).