In my experience, it's mostly a combination of confusing Lemmy UI + user error:
- When using the e-mail verification link, Lemmy just shows a blank page with a tiny "e-mail verified" notification in the bottom left corner, which people miss. They then assume that it didn't work, because all they see is a blank page.
- When opening the e-mail verification link multiple times, only the first time registers, and further attempts will generate confusing errors. This also makes people assume it didn't work, but in reality, their e-mail got verified successfully.
- On lemm.ee, it's very common for people to sign up with typos in their e-mail addresses (happens few times every week recently).
- We have a custom question on our sign-up page asking people to state they agree to our rules, and it's relatively common that people just don't read the question and write something random in there - we generally don't accept such applications to try and weed out bots, but I'm pretty sure we also end up rejecting a bunch of legit users this way who just didn't read the instructions.
Generally I'm happy to provide support to people in such cases if they reach out to me directly, but at the end of the day, the easiest and fastest solution if the account is truly stuck in limbo is just to create another account.
It's a shame that there is so much potential friction on sign-up, but at the same time, I don't see us reducing the friction on lemm.ee any time soon, because this is the lesser evil compared to bot sign-ups etc that we have seen in the past.