Seems like your focus is your rant about how people interpret Roguelike genre, therefore you don't need to quote or link anything from that person here.
First of all, genres are hard to define clearly and strictly for couple reasons. Therefore we have people misinterpret genres including developers.
Second, Roguelike has the word like in it, making it even more vague.
From my experience, I've read some developers labelling their games as metroidvanias however after I've played them or from watching video, I can say that those aren't metroidvanias. Some of those games are even using top-down view instead of platformer in fact. But that's my opinion and I have no right to deny those developers.
Same goes with Roguelike and other genres, we will see and hear more people misinterpret those genres . Despite this confusion, at least I could guess what feature I'd get from games claiming to be in those genres.
Last but not least, I agree with your last point. I don't like people branding some challenging games as Soulslike just because they are hard. It's just silly.