There are lots of features that open source databases still don't have.

How well does Maria DB handle distributed transactions across the database cluster?

Or how does Maria DB handle object based schemas?

What about the stored procedures language features versus PL/SQL?

Don't get me wrong, it is great that Maria DB is getting lots of money so that their developers can improve it, but there are lots of database features that keep us on Oracle and SQL Server, specially when we only care about business value and not FOSS religious discussions.