>>718793907
That's much more true in 1 than it is in 2. The only place your companions aren't that much help is inside the refinery, they can keep up and be very helpful for the vast majority of the game.
In 1 they start getting instakilled roughly around the Boneyard iirc and it never gets better. I wind jp just leaving Ian, Dogmeat and the others at Shady Sands and goinb solo once it gets too hard to keep them alive five seconds into combat.