Your reasoning does not make sense at all. I hope you're just missing GP's point. Maintaining a 1 meter distance has been shown to reduce the likelihood of contagion by 80%. Using a face mask has been shown to reduce the likelihood of contagion by 40%.

With that in mind, and knowing that these were only two of the many measures made to reduce the infection rate, your parahprased statement "the measures were meaningless because they didn't stop the epidemic" is completely incorrect.

An epidemic isn't on or off. It develops at different rates, exponential->logistic if R>1 and exponentially dampening if R<1 for each area. A very steep exponential phase will obviously cause the problems we have been trying to avoid, and it's similarly obvious that the defensive measures have prevented that outcome most places.

"Virus in the area" is not binary, on or off. It's always about rates and doses. Everyone is not infected instantly.

Germany provides a useful testbed for the impact of mask usage, because the mask mandates have been decided on local regional levels (federal state or city) at different times. From these different times of mask mandates and different progression of epidemic in the areas that are otherwise comparable, we can see that mask usage has a clear impact.

As said, it doesn't stop the epidemic alone, but it helps to contain it. To beat it, we need immunity through vaccines.

https://www.pnas.org/content/117/51/32293