The idea that suffering can have positive effects is in no way mutually exclusive with the idea that it is itself bad.

Here we're discussing definitions, I think. If you assume suffering is bad a priori, that seems to me to preclude there being (worthwhile) benefits from suffering. I find that difficult to swallow.

And this isn't just "surgery is worth it, even with the pain, but it would be more worth it without the pain"- this is looking at "no pain no gain" situations. Do they exist? I strongly suspect so. (I think many people overestimate how many there are, but that doesn't mean something things aren't better with a sting.)