One of the most-used close reasons here is
Questions about "how to get started," "what to learn next," or "which technology to use" are discussion-oriented
But this is not clearly stated on the Help page. The help page says not to ask subjective questions. I just had a comment exchange with someone who didn't read the Help, and posted this kind of question. I said to read the help. He came back and said his question wasn't subjective. So I said it was clearly stated in the help that "which technology to use" questions are off-topic.
Then I looked, and it isn't clearly stated. Maybe it should be.