I wouldn’t say “better”, because then people will assume, as you have, that it solves all of the problems with Reddit. Lemmy solves certain specific problems that are evident on Reddit. Namely the centralized ownership of the platform and the enshittification that can result from that.
It doesn’t solve the problem of certain bad-faith user behaviours like downvote brigading, trolling, etc. If anything, those problems are a bit worse in the fediverse since ban evasion is really easy. We recently had a problem with a troll who spent two months posting incel stuff to a variety of different communities, and when he got banned from one instance he would just create a new account with a different instance. He went through like 15 accounts, though he does appear to have finally given up as of a week ago.