Why do users only star a question as interesting but not upvote it?
I am new to Meta Stack Overflow, so absolutely any comments which are productive will be helpful and more information on what Meta Stack Overflow is for a novice would be much appreciated.
Everyone can mark a post as favourite, but not everyone can vote; you need 15 points before you can do the latter.
And starring a post does not necessarily mean someone liked the post; they could be bookmarking it to revisit later on, perhaps to see if the post needs to be closed instead, but want to give the OP time to improve before they cast the vote. Or they downvoted and want to make sure that the hilariously bad post is going to be cleaned up soon. They wouldn't want to upvote such posts. Starring a post is not the same thing as liking it.
I know I have starred posts in the past to verify that a OP is not going to vandalize the post again, for example; it is easier to keep tabs on a question that way.
Although the star is supposed to mark "favorite" questions, people use it just to remember a question they'd like to go back to. It does not mean they found the question worthy of being upvoted. There actually have been discussions on Meta to have system more flexible than marking a question as "favorite" to keep references to questions one would like to go back to, precisely because one does not always need to go back to a question because it is a "favorite". There are other reasons.
In some cases, I've seen questions come up on the scene with one star, probably indicating that the poster made it their favorite, probably so that they'd be able to come back to it easily. Or perhaps some posters think that if they mark it as favorite, it will have a psychological impact on voters (more upvotes). Since they cannot upvote their own question, this is one case why a question may have a star and yet not be upvoted.
And as others pointed out, not everybody has enough reputation to vote up questions.
