Well Beehaw’s rational is explained in this thread.

The reason I wanted to downvote was because Reddit communities like GameDeals is one of the new equalization I cannot easily find on Lemmy.

Thus, I found !gamedeals@lemmit.online / https://lemmit.online/c/gamedeals. It uses a bot to scrape the content from Reddit, but the scoring and popularity is missing.

When I joined there were only 13 people subscribed (now it’s 150+). If I’m limited to upvotes, it was difficult to “vote for the threads I liked” vs “vote for the shovelware” that appears in that channel.

With downvote, I was able to downvote shovelware and upvote threads I thought others would be interested. Everything else would be left as neutral.

I was on Beehaw and they block downvotes. I didn’t think much of it until I went to a federated channel with low participation (it was a new channel) and I wanted to downvote some bot-spam… but couldn’t cause Beehaw didn’t allow it.

I understand (but don’t agree with) the site operators intention, but their rational breaks down if you view the fediverse as something more than the single instance you’re registered with.

Fortunately, it’s easy to “vote with your feet”.