I think you're missing the problem for the consumer.

If I bought that game, because it means I could play multiplayer with my friends and now they are removing that feature <3 months after I bought the game, then I would not be a happy camper.

I don't think anyone truly expects a game's multiplayer should last forever, but it should last while the game is still popular and releasing updates.

Totally reasonable to be unhappy, sadly it's a common occurrence in this era of live services. Sometimes you buy an online-only game and the servers go down a month later. If you're lucky the devs will be nice and refund you, sometimes they don't.