I think the important part of the discussion is to separate the concept of protecting others from the concept of protecting yourself. As a population we can likely protect each other somewhat by wearing poor/basic masks. If it reduces spread by a few percent it's worth it
so long as masks are available without starving supplies in healthcare.
Healthcare staff must protect themselves as well, so need real protective masks. So long as those masks aren't available to healthcare, we should avoid buying them in the rest of the population. In the meantime perhaps a lousy scarf can be used.