No the magic was the community’s ability to weed out garbage so we can have meaningful conversations. Garbage is garbage no matter who wrote it.
Yet, it's possible to create a new account and get un-shadow-banned after a few hours. Dunno if this speaks volumes about how great HN's mods are or if it just means that other forums a really lacking in moderation for one reason or another (like "we have shitposts but it drives up engagement").
The trouble is that HN is centralized, like most forums. So what if it stops working the way it does now? There are likely many forums like HN with good algorithms and mods, but we won't all move to the same one, we'll scatter around. There isn't even a competing HN; lobsters is for narrower subjects, reddit is trash, what else is there?