Okay toss an S in front of FTP and we'll consider that fixed.
DNS isn't centralized. It's decentralized by design. Anyone can run a DNS server. Registrars maybe? But those are a dime a dozen too.
SMTP is only medium-centralized because it's a pain in the ass to run a mail server now due to spam. Anyone can still run a mail server and put in the work to make it not get blacklisted.
I don't get how TLS is centralized since we have dozens of entities that can issues certificates.
The protocols themselves are not centralized since a protcol is just a spec anyone can follow and build their own universe from scratch.
My critique is about how these protocols are used in practice. Because of their design, some centralize more easily than others.
You can run all the DNS servers you want but they have a single source of truth: 12 Root authoritive servers run by ICANN.
Freedom to use an SMTP mail is meaningless when 99% of potential receipients will just use a big email provider that will auto flag your niche personal mail server as spam. It's literally a cabal.
TLS is obviously centralized since your certificates have to be attested by an approved Certificate Authority in order to be accepted in web browsers and OSs. There's maybe less than a 100 CAs and they all have to be approved by browser vendors, aka Google.
