That doesn't mean that they are doing anti-competitive stuff and are viable for enforcement, being a monopoly in an open market is not illegal, it does mean that with that level of marketshare they have some legal limitations that their competitors don't have. Usually it's a limit on merges, acquisitions, price setting and bundling.
In the EU you don't even need market dominance to break anti-trust law, while in the US you do. In either case, Chrome is not committing anti-competitive behavior nor is it the only option on the market, hence it is not a monopoly.
Being a popular product in a market full of consumer options is not a monopoly. If Chrome prevented you from downloading other browsers, then that would be monopolistic behavior, but Chrome is not doing that.
It's not well received because, as GP said, people have the opinion that Chrome is a monopoly because they lack the empathy to understand that consumers are choosing something they don't like, and they would prefer it was a monopoly because they want a reason to break it up.