The upvote button is titled "This question shows research effort; it is useful and clear".
It's not obvious whether the ";" means "and" or "or", but it is possible to encounter a useful question that is both unclear and showing little research. One can't honestly upvote such a question.
But, regardless of its clarity or the efforts of its poster, a question can still be considered useful if it leads to useful answers.
I might very well answer such a question, believing that my answer will help other people.
Yes, you might say that I, myself, should edit the question to be more clear, or even edit it to add research to the details. But perhaps I don't have sufficient privileges to do that, or perhaps the question has several answers that would become incorrect if the original question were reworded.
Badly worded, poorly researched questions are still capable of generating good answers.