They didn't. The point is that they stop you from giving covid to other people.

Surgical masks don't stop you from getting Covid. That was never what they were for: they were to reduce the viral load you exposed others to, between when you got infected and when you noticed that you were infected. See https://en.wikipedia.org/wiki/Surgical_mask#Function.

Some cloth masks can (when dry) also trap small particulates through electrostatic interactions, although they are less effective as a mechanical filter than surgical masks; and many washing methods destroy this effect.

It was more nuanced than that and importantly, "Anti-masker" as a derogatory statement was about "This person is literally unwilling to do anything at all that doesn't pay off for them personally" because a goddamn mask is such a simple thing to do, and they just couldn't handle it, because it was someone else telling them to do something and some people just cannot function when that happens.

People lost their damn minds because "Hey could you maybe take a single small step to ensure you don't sneeze on produce" was protest worthy.

I do not believe someone saying "Masks made out of T-Shirts don't work well" or "Surgical masks aren't as effective as real N95 masks" are an "Anti-masker".

It was about vice-signalling. All the people who get pissy about masks do plenty of things for their "health" that have zero science behind them.

These people often did other things like hiding or downplaying any symptoms, and choosing to go to events while sick, and were often basically superspreaders.

This was all well understood like 25 years ago when WoW did that blood plague thing and people put effort into spreading it as much as possible. We've seen this with other diseases including ones that have no real controversy or political angle. Some people are just that insistent about doing everything they can to make the world a worse place.

It just sucks so much.