The goal is getting people to play Minecraft Dungeons together. “Minecraft Dungeons is designed to be played together with your friends – either on a comfy couch or in a comfy online session,” Mojang says.
And as the quote shows, Minecraft Dungeons still supports online play for friends. You just can’t get paired up with random people. Don’t forget as well that for a time, you’ll need to play with friends who own the game on the same platform as you; Minecraft Dungeons crossplay isn’t coming until later.
All this fits with what we already knew about how the team wants people to experience the game based on earlier Minecraft Dungeons dev diaries about level design and balance.