In aviation there's a situation that happens routinely, when a new design idea emerges in the experimental aircraft community (where what you can fly is only lightly regulated, as long as you don't take passengers), then makes its way into commercial planes. E.g. some new tailfin shape gets tried out and evolved by folks doing stuff by experiment using tools from Home Depot. Later on when the commercial guys want to adopt it, *that's* when the finite element analysis and wind tunnel tests happen. The prior evolution, successful and failed experiments, crash landings, etc. are all forgotten or unknown.
Is it not the case that medical stuff can come from e.g. two radiologists meeting in a bar, complaining about their crappy X-ray machines? They compare the good and bad features of existing machines, including the ones one of them remembers seeing in a visit to the Czech Republic (completely outside FDA purview), then introduce some new ideas of their own, etc. The initial "documentation" is napkin drawings made at the bar, that are lost when they get used to wipe up a spilled drink, but reconstructed afterwards. You get the picture.