Because many Democrats believe it does other things. Trump himself was quite explicit in his opposition to PP's abortion activities.
I’m sure it DOES “do other things.” But it’s crystal clear to all their clients “Honey, you ever have a pregnancy you don’t want? Or you don’t want this one? We’re right here to rid you of the problem. See, here’s a $100 coupon for Dr. Mengele.”
At some point, you don’t want to lend moral approbation to that because it’s organized around a main message.