This is exactly it - it's just genre bickering. "Roguelike" isn't a thing other than "sorta reminds me of rogue" and maybe ascii art is what reminds you of it - maybe permadeath (or maybe you never really perma-died - who knows) or maybe just obscure controls that had you frustrated.
Rogue has imparted[1] a number of interesting features that add strength to a variety of games - rogue-ish attributes are reflected in these games and that's about the total meaning of what roguelike actually means.
1. Assuming you don't attribute these to earlier games
There is a point to it though. With the number of games being released every year, especially in a genre dominated with indies, it is difficult to find games to play. Steam's tag are all over the place, with most "roguelite" games being tagged as "roguelike" too for publicity, and weird categories like "action roguelike" cropping up on any RPG with some degree of procedural generation. All the while, reddit's /r/roguelikes will not talk about anything that is not turn-based or outside of a tiled dungeon...
It is frustrating because it seems such a simple problem to solve, just use "procedural-levels"/"start-from-scratch"/"turn-based" tags or whatever terms the community can come up with, rather than stamping the attractive-but-now-meaningless "rogue" name on everything.
Not always. Genres and categories are useful to describe what it is like without sharing precise knowledge (i.e. finding an example that the person you talk with also knows).
I don't know what the sub-categorization argument is, but I kind of understand that people want to be a bit more precise. For instance, in the "object-oriented" category it is useful to distinguish "class-based" from "prototype-based".
To me, the lack of a commonly accepted definition of "roguelike" is a bit annoying because the definition of the term tends to become more and more fuzzy over time, to the point that the term will eventually become useless as a communication medium. So in my opinion, a little bit of gatekeeping is good.
Genres have suffered from the categorization problem [1] since the beginning of civilization. Since categories are made by people and people disagree on things all the time, our categories will disagree and conflict with one another. I think it’s just amusing how passionate people can get about it though.
