Sometimes the player should get frustrated. Without challenging them at all you run the risk of being boring. And that’s worse than straight up sucking.
There’s also a wide range of player skill levels to consider. If you aim to make a game not be frustrating for most players, it’s going to be boring for a large percentage of the best players. If you aim to make a game challenging for the best players, it’s going to be unapproachable for most. Different difficulty tiers of the same fight helps to address that but still alienates players if they find even the lower difficulties too challenging. It’s a delicate dance.
It’s been a while since I last played but the over-streamlining and continued simplification and homogenisation of the classes in combat was definitely part of the reason I stopped playing.
