The linked question does not meet the guidelines if there site or stack exchange. It fails in several ways: it is an opinion question "is it possible" questions automatically make it a matter of opinion.
It's too broad, by asking several questions. Questions should be specific, clear, and answerable. Multiple questions could in most cases be asked separately.
And as far as being on topic this is a gray area, asking a question about space elevators on a site where most people practice circuit design is probably not wise.
The OP has question that they should not have asked per the site guidelines:
you are asking an open-ended, hypothetical question: “What if ______
These two questions are opinionated and openended:
Is single-line power delivery physically possible at all? Is
single-line power delivery practical with probably available
That alone would invalidate the question, but the OP asked 5 questions, which is in most cases too many because to sufficiently answer all these questions would take more space and several pages.
I would also vote to close this question
Furthermore the topic is not really in line with the site guidelines:
This site is for electronics and electrical engineering professionals,
students, and enthusiasts. We ask and answer questions about
electrical and electronics engineering topics, which include
electronics, physical computing, and those working with
microcontrollers, Arduinos and embedded systems. We feel the best
Electronics Design questions have a schematic, links to pertinent
datasheets or some source code in them, but if your question generally
a specific electronics design problem
the theory and simulation of electromagnetic forces
a communication scheme
the writing of firmware for bare-metal or RTOS applications
IMO the topic is too outside the scope of this site, and is not about electrical design.
A better way to phrase this question would be "I have material X with Y conductivity, would this be a suitable material to be able to deliver 1MW of power 200km?" That is a design question that can be answered.
You have to have 5 votes from different reviewers to open or close a question, so most of the time (not all) an action taken it on a question is correct