It's total bullshit, I have no idea why you spread that misinformation.
By default, MariaDB uses the XtraDB storage engine, a performance enhanced fork of the InnoDB storage engine. For compatibility reasons, the system variables still retain their original innodb prefixes, and where the text in this knowledgebase refers to InnoDB, it can usually be understood as referring to the XtraDB fork. Note that it is possible to use InnoDB as a plugin in MariaDB instead of XtraDB XtraDB has more features than InnoDB, this is why it was written. It's a better, improved version of InnoDB which is very recommended. MariaDB is being used as a default MySQL database in many distributions, including Debian.
https://mariadb.com/kb/en/mariadb/xtradb-and-innodb/