The point i am trying to make here is that the X1 and WiiU had a debatably better line up which basically says that the console down falls and the PS4 up rise had nothing to do with the game library. All three consoles didnt have system sellers yet 1 sold incredibly well, 1 sold below par and 1 basically flopped.. this shows the power of marketing.
Also if you do a game comparison list and even do a meta comparison you will see my point in the 1st 2 years of these machines.
I don't know what the mythical "X factor" is. All I know is that I got a PS2 within the first few months and, up until Christmas 2001, all I had to play were NBA Street (I hated sortss games), Red Faction (I hated FPSs), Zone of the Enders and The Bouncer.
Aside from that, the pickings were slim. I rented Onimusha and beat it in a day. Time and time again, I went to the store and came home empty handed. If I didn't have a Dreamcast, I might have died that year.
The PS2 went on to become the best selling console, ever.
Just goes to show that there are a ton of factors that decide what wins for the gen.