No it doesn't. The fact that the article had to say "Maybe Redis for caching" because Postgres can't handle caching at scale shows that Postgres is not a perfect solution. Choosing an alternative database that can do everything you need means simplifying your architecture in the spirit of the article (not to say that MariaDB specifically is the right choice here, I'm not familiar enough with it to comment on that).

> because Postgres can't handle caching at scale

Which is the exact point the article is making. You don't have scale. You don't need to optimize for scale. Just use Postgres on its own, and it'll handle the scale you need fine.