No it's not, because it's very hard to set up in clustered HA environments. This is 2024. It should be possible to just add database nodes.
If you can run your own infra – at least on an EC2 level – you can do things like Citus [0] for Postgres, which is about as close to "just add database nodes" as you'll get.
Ultimately using something like Postgres in 2024 is just an on-ramp for expensive managed cloud database services, which is probably why it's promoted so much.
I think what you're actually observing is simply that Postgres is by far the most vendor-neutral DBMS (/API) available, and therefore the volume of conversation & marketing around it stacks up very disproportionately.
In contrast, asides from MySQL all other DBMS options require getting invested in ~one company and relying entirely on the whims & fortunes of their commercial support organisation.
A relevant article and comment thread: https://news.ycombinator.com/item?id=31425872
It's a fork of postgresql with distributed architecture, so you can add and remove nodes as you wish. And it's free if you self-host.
If anyone has experience with YugabyteDB (or any other multi-master PostgreSQL like DBs please let me know!)