Well, when I called it the "bottom line for me", I'm saying this one graphic is a pretty good encapsulation of my position, not that this is the end of the discussion.
And if masking is what drove the infection rate down as spring arrived, it should have kept it down as we moved into the fall. After all, the virus had thoroughly infiltrated Italy and other Western European countries by the arrival of summer.
And to be clear, I'm not saying that masks don't work at all. I'm saying I don't think they work as well as their proponents believe, and I absolutely don't believe they caused the decline in new infections from March/April on. I believe that was mainly a seasonal effect as illustrated by what happened this fall.
What I think does work is if you caught this very very early and implemented extreme social distancing (nearly absolute lockdowns), extensive testing, and shutting your borders and then only opening them after you had a testing mechanism in place for people coming in. But, I suspect that you had to do this before you had some critical mass of "seed patients". Once the virus achieved a foothold in a population by having enough infected people running about, those measures were unlikely to be able to win the day. I think this is what happened in South Korea. I don't doubt their extensive mask wearing has helped, but I don't think that alone would be near enough to explain their fantastic success.
Also, let's revisit Germany. We thought that Germany was doing something fundamentally different and better than the rest of Europe. But, if you'll look at their infection rates now they look a lot like the rest of Europe. So I see no evidence that they are really different than the countries around them. What I think happened is that Germany was for some reason seeded with much fewer initial cases in the Dec - Feb time frame, unlike her neighbors. Why I haven't a clue. But I think covid failed to reach critical mass before spring started which started driving the infection rate down. Unfortunately for Germany, I think they had a low level of transmission going in the background through spring and summer so that when we went into fall there was a sufficient base of covid cases that it was well positioned to break out with the changing weather. I think the same thing happened in some more remote area of the US like North Dakota. In fact, if you'll look at the graphs for covid deaths for Germany and North Dakota they look similar.
I think there was a race going on early this year in each county - how many initial cases were you seeded with from Dec - Feb, were you successful in shutting your borders and tracking those cases down, and if not was your initial infected population small enough that you didn't reach critical mass before spring came in and slowed everything down.
That's my speculation but it matches the data I think.