@Vashzaron Now that I check PSO2Global YouTube and Twitter, yeah, looks like they're using "online RPG" and "online action RPG" most of the time. They still called PSO, PSU and PSO2 at least in early days MMOs in Japan, but w/e. I think they made a mistake in one of the 2019 interviews or something, which is why I thought this is what they went for.
Anyway, the general public thinks PSO2 is an MMO. It's covered by MMO content creators (often with really dumb complaints), game journalism sites like IGN call it an MMORPG (yes, game journalism, but wider public still follows them). Some other online action RPGs like Path of Exile are also mistaken for MMOs, but PoE devs went out of their way to write this diary to explain what their game is actually about. It doesn't help that the game is always online (unlike its predecessors, as in PSO you could mainly play offline and take your character online sometimes, and PSU at least allowed to make a different character for offline mode).
Regardless, hack&slash is a very fitting label for the game and it communicates exactly what people should be expecting coming into it. Weight, precision, studying enemies and your own variety of tools (even if the game doesn't really punish you for not learning it all as fast as possible)