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.
Downvote do have a role… It sort of reading the room.
Sometimes the hot take is too hot, sometimes person literally spouting wrong information with confidence of ChatGPT. You don’t always have to engage.
All of this is true in “natural” social media tho once it becomes big enough too many bad faith actors get involved and no consensus can be built