By your definition then, whether you intended it or not, there are no distinct genres. I can take any genre of movie, and say that they have little to nothing meaningful in common other than X, Y, and Z.
What does the Terminator have in common with Raiders of the Lost Ark or the Fast and the Furious? They have about as much in common as Deadpool and The Watchmen. By your logic then, “Action Movies” are not a useful designation.
Scifi movies are not a useful designation either because movies like Moon and 2001 have almost nothing in common with Aliens, other than both having spaceships and taking place off of the planet Earth.
RomComs are not a useful designation because movies like Titanic and Eternal Sunshine of the Spotless Mind have almost nothing meaningful in common.
I could go on and say the same for every major genre of movies.
At the end of the day though, Deadpool and The Watchmen ARE superhero movies because that IS how people group them.
Movies belong to multiple sub-genres. Deadpool is a superhero movie, an action movie, a comedy, and a parody. It belongs to all of those genres and more. But the overarching genre it belongs to is the superhero genre.
Your point is… pointless.
And on a side note, I find it very telling that you’re seemingly incapable of distinguishing between my personal opinion of the Incredibles being the best superhero movie of all time, and me saying that everyone should think that the Incredibles is the best superhero movie of all time. I never said that, and if you disagree, that’s your opinion. People don’t have to agree on opinions. That’s why it’s an opinion and not a fact.
I guess I shouldn’t be surprised though. There have been many instances on this forum where you haven’t been able to distinguish your own opinion about something from objective fact or you confuse someone giving their own opinion about something to them and saying that everyone should feel or think the same way.