Can you site your source for this?
Delves, horrific visions and other content that can default with 1 player and scale up to 5 (would be even more awesome if warbound alts could sub in for real players).
I am well ok if only tanks can do the content solo in higher difficulties and dps or heals need to source a tank to push max difficulty. I am also well ok if some specs have an easier go of things because they are ranged, or have a pet or are hybrids.
Wow needs more drop in/drop out quick short contained gameplay loops (like delves)… maybe if M+ were 15 minutes instead of 25 (or hour).