If you hold a MPL as oppose to a CPL/IR, the qualifying criteria for ATPL issue are identical. You can only go down the MPL airline route if you are tied in to a specific airline. Eg. Flybe, BACF etc
So you are now issued with an ATPL, flying for an airline.
If you wanted to revert back to non airline flying, that is where lack of qualifying experience would come into play, as you did not do the Full CPL/IR light aircraft flying in the first place.