Even decentralized protocols trend towards centralization at scale. You might not need to use Gmail to do SMTP, but if you want your SMTP sent mail to reach a wide audience smoothly, you’re probably going to wind up buying SMTP forwarding from a centralized source that solves the “trust vs spam” problem. Same with DNS, you don’t need to use cloudflare sure, but ultimately your DNS is only as good as the root servers that everyone else is using too. DNS itself might not be centralized, but all the TLDs absolutely are.
That's not centralization. Specific providers might be more popular than others, but the user always has a choice of which to use. It's a myth that it's not possible to run your own mail server. Many people do so without issues.
DNS is hierarchical, so of course every provider will ultimately peer with the same root servers. And TLDs definitely aren't centralized. They're managed by different companies, and users can use any number of registrars.
It seems that many people here misunderstand what centralization is.
The fact that Google is the largest email provider doesn't mean they have a monopoly on email. That's ridiculous.
Yes, they can take advantage of their position to influence the market and strengthen their position, which would be illegal. They're arguably doing that with Chrome, as Microsoft did decades ago with IE, but that's a legal matter.
The difference with email is that it's possible to use it without depending on Google at all. It is a public service not controlled by any single entity precisely because decentralization is built into the protocols. Again, the popularity of individual providers makes no difference.
