Reddit (tries to) weigh the votes of bots, sockpuppets, and other no-do-gooders to 0, and the rest of us to 1.

Similarly, perhaps you weigh the votes of your friends to 1, your friend's friends to max(1,their_friends/10), and your friend's friends friend's to max(0.1,their_friends/100). Except for bob, who's votes you weigh at 0, because he's always getting his account hacked or suckered into yet another bitcoin ponzi scheme.

There won't be any single point of truth as to the "real" points of a post in this kind of model, but that's probably OK. Actually, there already wasn't: The same link in two different subreddits might gain wildly different amounts of points, with the subreddit adding as a proxy for a group of people who's votes you've decided to weight at 1.

Tech aside, decentralization just puts the onus for more finely deciding the weights of people's votes on the end users instead of on admins. With the right tools you can manage and limit abuse.

A flaw inherent in this model is doing admin stuff is probably more work than the average user wants to do, so such a model will probably never take off.

Quite possibly so; increasing the vote difficulty may help here; but one thing to keep in mind is that the proof of work voting is not necessarily the only voting approach that could be supported. The proof of working voting I think works best at a large scale of users something notabug doesn't have yet.

It was something easy to implement that works decently enough for now; but with a decentralized network different peers can experiment with different voting and sorting strategies.