I think the logic is that you, by virtue of the fact that you made the comment (or post), agree with the contents. If you comment or post but don't agree with what you wrote, you could manually remove the upvote. Alternately, you could just not make the comment to begin with.

If you’re worried because you feel like the app is trying to promote your post/comment by upvoting it, then don’t worry. This is the default action on lemmy (and Reddit). Essentially every post and comment starts with a score of 1, so that is what people expect.

If you were to find a way to disable this for yourself (or manually remove the vote), I think that your post will get buried because the algorithm “expects” a score of 1 and your post would basically look like it was instantly disliked, receiving worse ranking for anyone browsing by anything but New. Note, I don’t know exactly how the algorithms work, so it’s possible that I am incorrect here. I could also see the algorithm ignoring the OP’s vote and your post ending up in the same position.

Additionally, with a score of 0, people are more likely to skip over it, thinking it’s bad content. Or, even worse, hive-mind downvote it.