Anyone can register a second level domain under .com or the other main TLDs. This used to be the few main namespaces shared by everyone, at reasonable prices, and it went just fine.

ICANN made a de-facto distinction with the obscene pricing for top-level domains. There's a new global namespace, but you can't afford to get into that one if you're not a big fish.

That seems to be what the landscape looks like nowadays.