feeling xtremely constrained. do people write speculative fiction to get away with lack of knowledge and facts

Answer 1

Even if the facts an author is using are made up, it is still work keeping them straight. It isn't a matter of just making things up. A good writer will also have those things making sense and working together to make the story work. And quite often there is still research to be done. Many writers (the ones I know) borrow ideas from things that already exist. Myths and legends that they follow, or scientific principles that make up a major part of their story. The fact of the matter is, any amount of writing is hard when you're serious about it, so discrediting someone just because they make up their fact is absurd.

Answer 2

No work of fiction is really about 'the facts' but it certainly takes a lot of knowledge to write any book. (try it) Speculative fiction (or Science Fiction) is not Science and not meant to be.

Fiction reveals certain truths about human behavior and the human codition that is hard to explain with science. Fiction is an art and no art is ruled by the laws of science.

I find it ironic that you say thay you feel 'constrained' when its actually the opposite, fiction writers throw off the constraints of the real world in order to explore things like the imagination and emotions.