360 had a ton of system sellers. Halo 3, Gears 2, Mass Effect (at the time). Lots of exclusives people bought 360s to play.
I agree, a 'system seller' can mean different things to different people depending on their circumstances. I was a die-hard PC gamer until I finally picked up a 360 for Kinect Sports and Dance Central for social gaming. Rock Band soon followed (not exclusive) and then I stumbled onto Mass Effect and basically stopped PC gaming altogether a year or two later. The ease of use, and living room play, are what sold me.
As for the platform wars, I just don't get it. I initially bought a PS4 this gen due to Microsoft's E3 hubris, but later picked up a One as I missed the controller, the UI, and achievements. Actually traded in the PS4 in a few months ago as I never turned it on. I also have an i7/GTX1070/32GB which would blow the pants off both consoles graphically, but I rarely use it for gaming.
None of the various options is pricey enough that I could imagine getting into flame wars over it. I am a little annoyed at Sony for blocking cross-platform play though. It would be fun to play Minecraft with my little nephew, but not sure it's worth buying a PS4 just because Sony is being a stick in the mud.