Unfortunately, I can't answer the one about sales. That's a good question, though, and I'd like to an "insider" perspective on it.
As to this question, I think that again points out why tropes and genres aren't really that useful:
"But, there's a Big Bad if it's Action Adventure". No, there isn't, and let me explain why. That is only subjectively true. To me, it is completely and utterly false. The belief in it is largely the reason that I can't stand most Action/Adventure stories. It is wholly possible to have what one would perceive as an Action/Adventure story without what is called the Big Bad*. I prefer such stories. They do exist, but due to the perception that such a statement is necessarily true, stories that go against it are darn near impossible to find.**
The other problem with this type of classification is that there are so many stories that straddle the arbitrary line that must be drawn by the classifier, due to looking at the cover of the story, rather than the content, the face value rather than the argument. In Dramatica terms, the Storytelling rather than the Storyform.
To put the two paragraphs above into context, I loved the Disney movie Bolt. I personally would argue that it is an Action/Adventure movie, but it certainly does not have a Big Bad in the sense that the trope would require. Others would argue against me and say that it isn't even an Action/Adventure. Netflix classifies it as Comedy, which I can see, and Amazon doesn't even appear to try to classify it.
To take another example, it's extremely debatable as to whether Captain America: Civil War has a traditional Big Bad. Even with Zemo working to break up the Avengers, and the government trying to get the signatures to limit the freedom of the superheroes, I don't perceive either of these as the Big Bad per the trope definition. Some other person might, and they may feel free to do so, but I don't.
In both cases, the question boils down to where the arbitrary line of separation is drawn in each of our minds. Thus, if a story doesn't "fit" the genre (lower-case), well it might still be that genre. It's not a useful classification for figuring out what type of story is being presented, as much as it is in determining what kind of world to imagine visiting for the night.
*In terms of Storytelling, it gives the writer a relatively lazy (to me) way to source so-called bad guys for the so-called good guys to face. It can work well, but I haven't seen it work well recently, except when lampshaded for comedic effect, or when the focus is on the individual characters and their relationships instead of "saving the world"...
**It's also likely the reason most of these stories source conflict from Desires. (Reference: Subtext.)