The results in PA-18 sure do seem to make @Pinboard’s “I dunno, maybe run in every seat” strategy seem more viable than the “let’s run in not-every-seat because reasons” strategy...
I don't understand this belief that running candidates in difficult races is bad for them or the party. Above all, it's a gesture of respect to the voters in those districts, especially the Democrats. There are plenty of good people willing to run if given backing and support