In a previous question, L.Dutch, a moderator, noted as a standard that mecha were impossible. and so the burden was on us to explain why they were possible.
That very element making mecha possible in your world might be of paramount importance to answer your question, but the burden is on you to explain it. We cannot read your mind.
Sphennings noted their own criteria.
We expect questions to provide the relevant details. If I ask "How will my magic system do a thing?" I'd better describe my magic system if I want my question to remain open. In general we make an assumption of things being similar to earth, except when specified. If I ask "What is the maximum altitude a human could climb to?" I don't need to say no magic because that's implied by me not describing a magic system. But If I ask "How high can a wizard climb to?" a magic system is implied and better have the relevant details described.
But even on their own questions, L.Dutch, the mod, doesn't explain the background behind sci fi concepts. for example, immortals. Also, most of the front page questions don't explain the science or magic behind their decisions. The masquerade question doesn't explain the scope of the masquerade, even though that would help with defining how the rules should be made. A question on wing maintenance for a demon angel hybrid doesn't explain how the magic or science of the angel or demon works, even though that could help with cleaning, and humans flying is scientifically implausible without some large changes.
Is there a list of topics that do require the burden of proof and don't? Which require an extensive background on how the science or magic works? Like
Burden of Proof required. Mechas. Superhumans.
Burden of Proof not required. Angels and demons. Magical society. Immortal humans. Cities which can walk.
At the moment it's hard to do questions without knowledge of which criteria will cause a question to be closed and which will be fine and accepted. Some clearer criteria for moderation would be valued.