It's the least worst system that allows for anonymous people to participate (no accounts required). Rather than stopping people the idea is to add just a little friction.
To say that, you're kinda assuming the objective though and then suggesting that it's a worthwhile one.
Like, this poor solution is probably the best thing on some dimension, I would just wonder if it's a dimension worth caring about.
The objective seems to be eliminating the requirement of registration at all. Why? Why would I care to enable people to upvote/downvote content that don't care to spend 1 second registering? I also don't think you can make a convincing case that the friction of registration makes or breaks any websites when almost all of the most popular websites require registration. Seems to be me users are willing to jump the hurdle by the millions if they care to engage.
It can't be a matter of privacy because the site could be logging your IP address in both cases.
It can't really be friction because you could make the most frictionless process possible. Maybe clicking upvote summons a tiny tooltip where you enter a username and password. EZBoard forums back in the day had that -- You would write your whole post and the submit button would assign you a random username that you could then customize.
I just see a forum that made the questionable decision to let you infinitely manipulate rankings without even trying to stop you, the actual impl of that (no registration, PoW puzzle, etc.) rather irrelevant.
