You called Destiny 2 casual friendly by playing 2-4 hours a day, and now that's too much time for a casual to manage?
Also higher difficulties are more about skill than gear. Yes there are gear checks so a player needs X amount of hp to survive a mechanic, or be able to do enough damage/healing but there gets a point where gear progression slows down massively and it's about everyone performing their part correctly to kill a boss.