Questions like this fall into a grey area that's a fuzzy set between science-based and science-fiction. My interpretation was the OP wanted a FTL drive with something approaching scientific plausibility. This isn't the same thing as scientific reality. It just needs to be grounded enough in science to sound better than just turning on a FTL drive. If it's a wormhole drive or translocation-drive, that sounds more scientific and many readers will expect that. Of course, there will always be readers who don't.
After all, no-one objects to vampires in vampire fiction, because the blood suckers don't exist. They're a fictional convention. FTL drives are a conventional contrivance of science-fiction. Even if they're impossible, there will be writers and readers who want make their FTL drives seem more scientific.
The issues about questions and answers and how they're edited are extremely complex and fluid. Some questions have answers that are blatantly wrong or illogical and receive lots of points. While good answers are ignored or passed over. Not always, of course, but enough of the time. This is offset by the sheer brilliance and quality of other questions and answers filled with well reasoned arguments and a breadth of knowledge displayed by people who do have expertise.
The tags should be better regarded as sign posts pointing the way to what the questions and answers are about, and not absolute arbiters of content. Any system or theory of classification always runs up against this realisation.
Only conceptual sets are pure. The real world is filled with impure and inexact groupings of everything and anything. Where tags fall short they can be refined but they will never be made perfect. Maybe tags can be improved in the long run, but this will only happen in small steps. That doesn't mean people shouldn't stop trying to get them better.