The notion that the top scientists in the fields of aerosol transmission and infectious diseases are "abusing their credentials" is, well, your opinion, and you are entitled to it. Among the evidence you ask about, in countries were masks were already a cultural norm, Covid infection rates have tended to be lower: https://www.atsjournals.org/doi/full/10.1164/rccm.202004-1188LE. Another study (in preprint, not yet peer reviewed) of 198 countries finds masking helps: https://www.medrxiv.org/content/10.1101/2020.05.22.20109231v5