Because for a lot of people it will spare them the time watching this by simply knowing that detail.
Also the main reason he gave MS the higher score was because Xbox One has the better line up for 2015. I completely agree with that fact, but we already knew that before E3 and that's not what an E3 conference is about. If this review was about what system hade the better games for 2015 then fine, but this is about the E3 events. And like i said he also hypes up Hololens(wich isn't exciting for gamers so far at all).
To sum it up he literally substracting a point off Sony's score because they spend some time on their Disney deal.
Again your opinion. To others E3 is all about this year. To others it is all about the future. To some like me it is all about a balance. So I would 100% agree that MS won this E3, but that is just me. As for Hololens what they showed of Minecraft excited a lot of people. Just saying.
Its libraries that sell systems not a single game.