Well, a lot of that boils down to actually "putting in the effort" to have sane-ish distinctions (the bar is low). You'll see similar arguments from the milsim crowd, for example. Same with a lot of flight sims where there are generally pretty well understood criteria for the different subtypes (even if it is a mess to find a way to refer to stuff like "Lock-On" that is not "arcadey"...). This isn't "Well, it has a level up animation so I guess it is an RPG". This is "It meets criteria X, Y, and Z so it is a roguelike. It meets only x and y, so it is a roguelike. Why do you keep bringing up Operation Flashpoint?"

Contrast that with something like FPSes where you can vaguely distinguish the different eras but there is a lot more bleedover to the point of (fucking stupid and borderline offensive name aside...) not actually being sure if DOOM 2016 is a "boomer shooter" because of the design decisions... even though DOOM is the gold standard for both 2016 and stuff like Dusk (actually Quake was, but DOOM markets better).

Like, I assume most of the crowd are too young to remember but there were actually REALLY big arguments over "MMO" back in the day. Maybe we all remember the question of "So... is Destiny an MMO?". But there were a LOT of arguments over Guild Wars 1. Because it looked like an MMO and it even progressed like an MMO but... it was Diablo 2 with a fancy skin for the IRC chat room between instances. And a lot of people (kind of rightfully...) blame Guild Wars 1 for the mess that has resulted in "Diablo 4 is my favorite MMO".

Which, getting back to Roguelikes/lites... as long as you listen to WHY something is not a roguelike, it is a really good distinction. If the reason involves progression mechanics then you almost immediately know if you care. And if it becomes one about aesthetics, you know nobody, not even the person bringing it up, really cares.