For the cartoon itself you are right, but context is important here and it came with a text. It clearly does state that it shows that masks are important. Let me show you, emphasis is mine:
I'm sorry, but I just can't see how this cartoon is any helpful in the discussion about the effectiveness of masks.
Before anyone takes this out of context again: I do know and do believe in the layered approach. No problem there. But there is more to it. The drawing does assume things like the fact that each of the layers has a relatively moderate positive effect and ignores the possibility that some of the layers might have negative side effects.