You're both right, but you're also both wrong. There's a big difference between protection for the user and protection for others; surgeons aren't wearing masks for their protection, it's for the patient. Surgical masks are actually a great example of something that has little protection factor for the wearer, but is effective at protecting someone else in the room. There's also a big difference between a cheap, single layer, polyester gaiter and an N95 (Unreal has been trying to point this out for like 1,000 pages). I am under no illusion that my cloth mask, over my bearded face is providing me with any real protection, but it will greatly reduce any spread of virus if I happen to be a carrier. Particle size isn't super relevant if the particles are borne in a suspension; if the mask can stop or slow the droplets or vapor, it's helping.