Not true. I hear it used in the manner described in the OP all the time. I understand how it’s currently used.
It’s a combination of generalization and specialization that I’m thinking of. The usage defocuses to include more meanings, but then refocuses in on something different than the original. I.e., A → A+B/A+C/A+D → A+B → B. I suppose this alternating pattern is probably common and allows meaning to travel great distances.
Here are two fun examples (just read the few paragraphs of text):
At the risk of having the question of “what in the hell is a vtuber?” raised, here’s an example of the modern usage of ‘lowkey’ in the wild; Enna uses it three times in under three minutes in this clip. Enna is a Canadian vtuber of Philippine descent in the vtuber group Nijisanji; she is probably in her 20s. Enna meets a Hot but Nerdy Watch Salesman with her Mom - Nijisanji EN - YouTube
Good example.