I think we're all familiar with the Karma system on Reddit. Do you think Lemmy should have something similar? Because I can see cases for and against it.
For: a way to tracking quality contributions by a user, quantifying reputation. Useful to keep new accounts from spamming communities.
Against: Often not a useful metric, can be botted or otherwise unearned (see u/spez), maybe we should have something else?
I don’t think it necessarily needs karma like Reddit, but I think a reputation system of some sort is going to be required for open federation to remain viable as federated systems grow. Just looking at account age and post history isn’t good enough if the bad actor owns a server and wants to put some effort into spamming or harassing people.
Which is why the reputation system can't be based on something the user's server says, but must be based on third parties the person checking the reputation trusts.
You can check that manually by looking at the user page on lemmy.world and see that the posts were not removed by the community's moderators, but you cannot check that the account is not banned as far as I know. What I have in mind would let your server query that sort of thing automatically and set up lists of communities you'll trust to vouch for users.
There could be several options to deal with a user who doesn't have reputation, such as not letting them post, holding their posts for moderation, or having a spam filter scrutinize their posts.
There have been efforts to build reputation systems that don't rely on central servers, like early day bitcoin's Web of Trust, which allowed folks to rate other folks with public key crypto, thus ensuring an accurate and fair trust rating for participants, without the possibility of a middle-man putting their thumb on the scale.
One problem with it is that it was still perfectly practical for bad actors to accumulate good ratings, then cash out their hard-earned reputation into large scams, such as the "Bitcoin Savings & Trust" (for $40 million in that particular case), which quite possibly made it measurably worse than not having a system that induced participants into making faulty judgments in the first place.
I think the main practical value of something like reddit's karma is an indication of age and account activity, both of which can probably be measured in other, if less gamified ways.