Yes and no. I think you should always explore the areas from boss to boss and discover whatever is there. But if a boss is too hard, or frustrating, or you just want to move on to the next area to explore, you shouldn’t feel bad about summoning some help. Or offering yourself as help.
I do think the game is designed in places to be played co-op. And as someone mentioned in the DS3 thread there are areas in every game where invasions are welcomed, or at least considered part of the design.