The way I remember it, was that MySQL was sold, then some time after, MariaDB was created as a fork, and you could switch between them. Then at one point MariaDB diverged sufficiently that you could no longer "effortlessly" (kinda) switch between them, by now they're separate but MariaDB's origin is still MySQL obviously.

I had the same immediate reaction. It's a completely nonsensical comparison which just demonstrates the author is extremely confused about the relationship between MySQL and MariaDB, in terms of their corporate entities and project structures.

That said, it seems to be a common point of confusion among FOSS die-hards, but still super unfortunate to see it repeated in this context!

mysql was pretty much the downstream thing that everybody used back then.