I think other FG content can be collaborative too. Look at Soulcalibur 2’s Conquest mode where you are contributing to something on a grand scale that’s not necessarily tied to PvP
People have to understand that one-player content in a Fighting Game doesn’t have to be a “mode” like Subspace Emissary in Brawl. I know I always praise them, but Home-Run Contest and Break The Targets in Melee are great one-player content that are fun AND make players better.