One explanation I’m thinking of is that different people have different views of what an upvote/downvote represents, especially if there aren’t very clear guidelines on it. Or if they are coming from a different social network where a downvote might instead mean “I disagree”.
This reminds of the 1-5 star rating system issues, and how people interpret it however they want without reading what it means. Let’s take Uber for example. I leave a 5/5 rating for a purely average trip where everything went as expected. Afaik, this is how Uber’s rating scale works (apparently drivers start getting warnings if they drop below ~4.5), so it surprised me when I once saw a friend give a 4/5 since the trip was “just normal/average”.
Conversely, let’s take Goodreads, where I feel that many people don’t read the definition of the rating scale and give star ratings not matching the definitions.
Goodreads definition is: 1 star="did not like it", 2 star="it was ok", 3 star="liked it", 4 star="really liked it", 5 star="it was amazing".
With that, if you simply found a book “ok”, you are to give 2/5. If you simply “didn’t like it”, then that’s a 1/5. It shouldn’t be unexpected to see many 2/5 and 1/5. And a 5/5 should be a rarity. Yet you if look at the actual reviews, feels like many people don’t follow the rating scale definitions and give it their own meaning.