Why does MariaDB still use the "mysql" name everywhere within the file system? I understand that MariaDB forked a version of MySQl but is is very confusing to still deal my.cnf, /usr/share/mysql , /usr/lib64/mysql and so on? Are there any reasons, why they did not change the naming on most of those folders? This had been very confusing to me and that is the reason why i have not migrated to it yet. It's either you are MariaDB or MySQL but don't try to be both.
MariaDB is a forked version on MySQL that attempts to be a drop-in replacement.  A good drop-in replacement should work without requiring a lot of configuration and data file movement.  By using the same directories and filenames, it is far simpler to install as a replacement for MySQL.

I haven't tried MariaDB, but I would expect to be able to install it test it, and decide if I want to revert back to MySQL.  While I would backup my databases, I don't expect to have to restore my data whichever option I pick.