Some subjective questions are allowed, but “subjective” does not mean “anything goes”. All subjective questions are expected to be constructive. What does that mean? Constructive subjective questions:
inspire answers that explain “why” and “how”
tend to have long, not short, answers
have a constructive, fair, and impartial tone
invite sharing experiences over opinions
insist that opinion be backed up with facts and references
are more than just mindless social fun