I think this is a key difference - where MariaDB continues to evolve MySQL 5.6/5.7 codebase Oracle chose the "big leap" with MySQL 8 - introducing data diction

I think this is a key difference - where MariaDB continues to evolve MySQL 5.6/5.7 codebase Oracle chose the "big leap" with MySQL 8 - introducing data dictionary and many other internal architecture changes. This is one of the reasons migration to MySQL 8 can be more painful than releases before it but for good reason