It doesn't imo. For how I see it, the MMO aspect strengths are battles, teams, economy, and I don't see how this affect any of these things. I wouldn't say looking for someone to evolve a pokémon is a key aspect of the MMO thing, as it works just like any mainline pokémon game.
If someone doesn't want to interact with people but needs to evolve a pokémon, he/she can still trade with an alt account and keep playing alone. If he/she wants to, the option to do it the old fashioned way is still there. There would be no radical changes regarding this.
These are great points! The social