So, the fact that an original question does not have any upvoted or accepted answer precludes others being flagged as dupes. I don't see the rationale for this. The nature of a dupe would not depend on the answers, I guess.
1. Can someone explain the rationale?
Note 2: I found a few questions Q1, Q2, ..., related to this one in Meta, but if I understand correctly they do not ask the same as I am asking here. Moreover, they seem to imply that the OPs of Q1, ..., do not see the limitation I am seeing
2. Can someone explain why these other people can apparently flag dupes under conditions I cannot?
PS: 4. What should I do If I can't flag as duplicate because answer is neither accepted nor upvoted? sees the same limitation as I do.