Maybe not an eli5, but lots of reasons.
There’s no stable, consistently updating client that everyone agrees on, the real ‘emule’ client hasn’t been updated in over a decade. Once you get past that hurdle, the setup is also a lot more cumbersome than other file sharing options. The network also has kind of a bad reputation because there’s not a great way to see if you can trust a file until you’re finished downloading it and people definitely do take advantage of that.
It’s similar in a lot of ways and this is still an echo chamber and the echo chamber we have here has a lot of overlap with reddit… but, while reddit mostly just leaned left… Lemmy… just leans anti-west. As mentioned, there’s a lot of overlap there, we’ve got a lot that is shared, but the parts where those two groups differ can cause some serious wtf moments if you’re used to the reddit community. As far as over policing, moderation logs are mostly public and there have been some controversies, but mostly people just stopped caring or left. If you stick around long enough, you will notice policies being applied unfairly if you’re on the ‘wrong’ side and it’s a lot easier to be in that category here.
All that to say, you’ll likely have some moments where you think… Maybe that old echo chamber wasn’t so bad.