Correct.

PDO is great because one API works with many technologies. So today you're working with MySQL, but tomorrow you may be working with postgres, and the next day sqllite or MSSQL. It's nice to not have to relearn everything (sure each technology will still have quirks, but largely they work the same with PDO). That flexibility comes with a few limitations, because if one technology supports it and another doesn't, that defeats the whole "one API to rule them all" thing.