That source has this bit however:
One of the first studies to test how environmental conditions affect viral transmission was published in 2007, and it looked at how influenza spread through guinea pigs infected in a lab. High temperatures and in particular high humidity slowed the influenza spread, and at very high humidity levels, the virus stopped spreading completely. Warmer air holds more moisture, which prevents airborne viruses from traveling as far as they would in dry air. In humid conditions, the small liquid droplets in a cough or sneeze gather more moisture as they’re expelled. Eventually too heavy to stay airborne, they drop to the ground.
Which would suggest that masks, which both act as a barrier and keep your airways warm and moist should have some effect.
It's just common sense. Naturally, it's already been studied:
https://www.huffingtonpost.com.au/entry/do-face-masks-prevent-virus_l_5e304a13c5b6ce51a4ec0a09There is some evidence that, when used correctly, face masks can slow the spread of airborne viruses. For example, one study from 2008 found that those who used a mask were 80% less likely to get the flu. Another 2009 report found that, in tandem with frequent hand-washing, face masks lowered people’s risk of getting the flu by about 70%.
So that's strong empirical evidence, along with the above reasoning-based argument, that wearing a mask could confer general protection, along with explaining why.
The reason there can be conflicting arguments is due to faulty or incomplete reasoning. For example you could say "face masks leave 99% of the air passing through them unfiltered, therefore they can't possibly provide any protection against viruses - they let all the viruses in!" The problem here is that the argument itself is faulty. The facts weren't wrong, but the conclusion was wrong, because the facts given don't automatically imply the conclusion. A ton of assumptions are made, which remain unspoken: the assumption is made on how masks are
supposed to work, the masks are then shown to not work that way, then the conclusion is given that because you disproved that one way, then masks can't possible work
at all. It's like claiming that trees grow from eating the soil, then noting the amount of soil hasn't decreased, then saying as a conclusion that trees don't grow.
We just have to look at the study showing that mask users got 80% less cases of the flu to realize there
must be a flaw in the argument. Maybe the mask users got less flu because their nasal passages were kept significantly warmer during the high-risk periods that they were outdoors, and it had nothing to do with filtering viruses.