What I mean is that this is regulating at the wrong level, or perhaps that regulation is a poor substitute for what might be more useful. If there were more competitors in the phone side of things, then mono app stores would matter less, and if people cared about them, eventually get competed out.
The problem I'm highlighting is that the EU itself hasn't created any phone OSes that have survived to this point. If it were more conducive to that, then regulation, which is a very poor substitute for actual competition, wouldn't be needed.