That those two loathsome websites are still up doesn't mean that the technique I described is invalid; it just means it doesn't have a 100% kill rate, and it certainly works on less resourced and less indefatigable targets.
I'm not worried about those specific websites -- I'm worried about the increased spread and normalisation of the "contact everyone %s has a business relationship with, and shame them until they drop them as a customer" tactic. Where does it end? We've established that pressuring domain registrars and hosts is fine; what's fair game after that?
Is it fine for me to pressure and suborn an electric company into cutting off service to someone I don't like (after all, without electricity, they can't make those bad internet posts!). If I can rile up enough of an internet mob, can I get them evicted from their residence, simply by annoying their landlord until the trouble's not worth the monthly rent cheque? I've seen firsthand these tactics used by internet mobs and it's a very ugly process, and it's not something whose prevalence I'm happy to see expand.
Just because in these cases the targets are generally disgusting doesn't mean it's something that should be tolerated (if only because those who you hate will positively relish a chance to use that against your side of things).