My 2 cents as a sysadmin who has worked with countless systems and databases: there has never been a more unintuitive database system than Oracle (atleast from the administrative side).

Anecdote: Back when I was just an apprentice, I was tasked to duplicate an Oracle database (the Oracle guy just left the company). It took me over 3 hours to figure that one out (exp vs expdp, FULL=Y and OWNER=FOO come to mind).

And don't even get me started on PDBs and usernames starting with "C##"!