That's... that's not what "distributed" means. DNS is distributed because it's arranged as a tree, with the root nodes delegating to the TLDs delegating to individual name servers for each zone. Just because someone chooses to use a service instead of running a nameserver themselves doesn't make DNS centralized.
If a bunch of people choose a single DNS provider they all create a centralized point in this tree, through witch all of the clients wanting to access their services have to go through. This is exactly what centralization is and is exactly what caused downtime for a lot of websites when Dyn was DDoSed.
Redundancy and high-availability is something DNS has by design. DNS providers are incentivized to highlight those things as if they were unique to them, but actually the only thing they can offer is anycast for lower latency. Incidentally anycast also makes them less reliable, not more.
