That would be the "reanimated" part of "reanimated corpse"; I think you've significantly misinterpreted my point there. MariaDB is not dead; it's undead. A zombie. Or perhaps resurrected and now serving as a database messiah. Whatever the case, it's the end-result of something that's dead (MySQL) no longer being dead.
Looks like to me, like it is far from a corpse: https://github.com/MariaDB/server/commits/10.1
I agree with you on both PostgreSQL and MongoDB, but saying MariaDB is a corpse is ignorant at best.