I think it’s fairly well established by now that at least part of the initial advice against wearing masks was because the federal government bungled the stockpile and wanted to prevent a run on remaining retail inventory. Which is a shame because it seriously undermined their credibility and lent much fuel to conspiracy theorists.
(I have a workshop long stocked with both disposable surgical and N95 masks and reusable P100 masks/cartridges, so I have no skin in the game.)