I read an article at wikipedia which said that Quicksort can never sort as quickly as Merge Sort!? In its worst case Quicksort's O-complexity is O(n˛), whereas Merge Sort will never have any other O-complexity than O(n*log(n)).

I am wondering why the 'Merge-Sort-algorithm' isn't called 'Quickest-Sort-algorithm' then.

Are there any really serious drawbacks to 'Merge Sort's' optimized speed of sorting huge amounts of data - compared to Quicksort?