Immortal is an MMO, so I am not sure Solo was a core feature of that particular Diablo game. I say this as a Solo player, even in Diablo games. I LOVE some of the features that Immortal does have though. The footprints on the map, clear target markers for quests/activities, auto nav once you unlock that zone, great tutorials for game features, text to speech, colorblind options, screen flash/contrast options, lots of controller compatibility and configuration options.
While some players with disability issues, may prefer to play solo (I do), others don’t so they very much want to ensure they have play options as well.
That has not been great in gaming overall but has been changing the past several years across the industry. Something I highly support.
Also note, WoW, as an MMO, is not set up for solo play - and it is something I have asked them to change. It does not have to give the best loot, but I want to still see the story, be able to learn dungeon layouts etc. I made a thread about it when the Council started.