I can see how a blacklist org might want to lean on the owner of a range, but there's no genuine or 'valid' reason to punish the non-spamming IP within it (some of which may have no relation to the owner) other than pigheadedness imo.
I think you answered your own question. If I'm a non-spammer and the IP that I use is blacklisted because I'm hosted by someone who also hosts spammers, I end up moving elsewhere, which deprives the host of revenue. That's part of the way the blacklist leans on hosts to get rid of spammers for real instead of making empty gestures.