A lot of the huge grossing games (revenue over copies/boxes) are mmos but not rpgs. They have a persistent world with usually hundreds of players depending on the environment. I think the most common is where you have a town and deal with other people (clash of clans and its variations etc) but there are many knockoffs. These will have their own minigames and shit inside to keep interest going. They provide all the social elements of an mmo but little to none of the rpg grind elements, and often gatekeep to prevent degenerate play from getting a nolife edge. Instead, they almost all go major micro transactions heavy with huge diminishing returns.
These are the modern mmos. These are what kids that would have been mmorpg gamers 1-2 decades ago play. Its not the mass multi-player and online thats dead, its the rpg side of it, which is harder to monetize and harder to regulate/cs both, making it a big loser for a gaming company. If mmorpgs had real return on investment potential, you'd probably see better efforts by major studios. They don't though.