If you guys took the time to see the videos and the walkthrough you'll see that he doesn't relying on companions at all, besides the first time he encounters them. He plays completely alone, since the Companions kills would counts as actually kills in the game data.
So he's using smart thinking to solve XP gain with low intelligence and Idiot Savant, by crafting in settlements until lvl 10, than doing quicksaving to proc Idiot Savan when completing quests. He's also relying on stealth to go hidden from some enemies, and getting quest items without anyone seeing him.
In the start he couldn't pacify everyone, so he used smart ways to attract enemies towards other enemies. Than he starts to passing through dangerous places by pacifying the enemies with help of quicksave.
Than he started to use the attack command on pacify enemies to manipulate enemies and make them kill each other.
He's using dialogue to get some extra Charisma checks, so he can get more money, or to solve things without combat or having to do it himself. He's some quests by just talking his way through. Of course not all of them. And some quests that he needs to go accompanied someone else... that person do the job for him. Sometimes is a companion but since It's the first mission before he's actually is available as a companion, the game doesn't count those kills as yours.
It's not the most easy way to play, not at all. Specially at the beginning... but it's possible. Honestly I don't see why people is so much fighting over this. I do understand and agree that FO4 is more action driven than FO3, but I wouldn't say at all that this game is just Kill Kill Kill.
There are a lot of new things I didn't knew there. For example, meeting your companions in a non predictable order (as the game devs would think you would meet), unlock new dialogues and different reactions from them. Of course the main quest like and dialogues remains, but It's interesting that they put the time to record and do this different encounters.