I agree but it's not as bad as the "if you throw out April the Angels were the best team ever!" nonsense, as the whole point of the season is to win games. Margin of victory doesn't matter as much though. Giving up loads of runs in one game that's already going to probalby be a blowout loss is not as bad as consistently giving up several (but not boatloads) of runs and losing multiple games, even though stats like ERA, WHIP etc. would be the same in those two scenarios.
This was demonstrated by the Orioles who lost lots of blowouts and won lots of one-run games, they actually had a good winning record with a near-zero run differential.