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.
Problem with downvotes is people assume they feed the algorithm. They use them to say " I personally don’t want to see this". When they’re really meant as " this is inappropriate for this community".
I think Lemmy needs to create an algorithm that would help with downloads acting as expected. And then allow people to flag separately if something is not appropriate for a community.