Yeah, but why would I use that over PostgreSQL? I already know postgreSQL and it's also THE gold standard for SQL implementations. AFAIAC PostgreSQL is the obvious choice.

You would use it over PostgreSQL because it's a drop-in replacement for MySQL. PostgreSQL is not.

If you're not using MySQL in the first place, why would you care?

Because sometimes I DO use MySQL because a client requested it. At this point, I'll probably just explain to clients why pg is a much better alternative.

From a fresh build, I agree with you.

However, for MySQL in an existing application, the migration costs might make it not worth it. There can be a number of pernicious gotchas that aren't obvious at first. MariaDB is more or less set-and-forget.