cal1s: since the release of the game i've been watching an incredible skilled streamer who plays on hard/unfair. he is in act4 right now and about to finish the act soon. until now he killed every single boss on hard and on unfair (!) with only the companions. no mercs!
so yes. even with companions unfair is possible. but you need to know exactly what you're doing and you have to have a very deep understanding of the rules and mechanics.
i want to emphasize he is not using any exploits or cheats whatsoever. so yes, again, unfair is possible.
What actually brings us back to what people refer/define as "cheesing". What sounds like making bad analogue aka fake cheese I consider a combination of exploits of game mechanics and of course by doing so using optimun builds. Both only doable with having an extensive knowledge of what awaits you and experience.
There is an interesting forums thread on Steam which I find fitting for this thread:
"A lot of the most recent posts, seem to highlight just why RPG have been dumbed down over recent years, most have been make a cake walk and so easy to understand it borders on patronising, and yet despite this some gamers are still able to find them too complex.
To hear people crying that they want to have the achievement for finishing on unfair, and then to cry on the forums unironically about how "unfair" it is. Or literally have someone state that Owlcat is to blame for not teaching someone how to play the game, this stupidity works in no other walk of life,
"It is the failing of the supermarket that sold me the potato peeler, for not giving me adequate guidance" has been said my no one, ever.
Please stop embarrassing yourselves with these posts. I really do not want to see the last game that actually seems to some what respect the fact some gamers have a brain.
God imagine the outcry if you tried to make a morrowind game now."
https://steamcommunity.com/app/1184370/discussions/0/2963922521553874512/
So yeah, it is called "unfair" for good reasons in my opinion.