By default, Lemmy allows downvotes globally. However, when a server disables downvoting, it is similar to using a feature that is usually reserved for enterprises and very small, non-federated communities.
If a user prefer to not see downvotes, they can disable it by his favourite client settings, but the rest of the community should not miss this functionality for the pleasure of few users.
Sellers being also part of the problem is a fair point. But it isn’t just about Lemmy being Lemmy; it’s that unless a community disallows sellers, amateurs eventually leave.
This would probably need a different approach, like different comms for sellers vs. amateurs. Or, if the tag system were to be implemented, forcing people to tag their content accordingly.
About sexuality: the reason why I think that tags would’ve worked is that, once legitimate-but-shortsighted users stop downvoting things based on their sexuality, the trolls stick out like a sore thumb. And then you can simply kick the trolls out.
I usually browse top 12 hours or scaled and I haven’t seen an actual amateur post in a long time, so I think you must be right.
I think the sellers would get upset of not being able to mix their spam outside their comms, but I agree.
Altough I don’t have hopes for a tag system for a while, being careful of the tags not overlapping accross instances sounds like a pain.
At this point, I think everyone has blocked whatever they don’t like (based on sexuality), so if that hasn’t worked enough to stop the massive downvotes I doubt a tag system would work for that (since they don’t only come from one instance and sometimes they create instances for that purpose).