Doesn't it depend on the purpose of the list? If you are listing things that can only be played on one brand of console, then the cross gen exclusives go on the list. If you are listing games that can only be played on one specific console then the cross gen games don't go on the list. If you are making a list to try to demonstrate some sort of difference between 2 consoles not of the same brand then cross generation games would go on the list. If you're listing games as the reason people should upgrade from last gen to this gen, then obviously cross gen games should not be on the list.
If people were clear in communicating the intent of their list, then responder will have a sound basis for judging whether the list has all legitimate entries or some illegitimate entries.
I think in the case of LBP3 there would have been noise from Sony fans if it was PS3 only, but other than that it seems like it's a good addition to the PS4 library even though it won't push hardware sales forward. I expect it is a system justifier though. "hey honey, I can buy a PS4 now because there's this really cool game for the kids, so we can make it a 'family' Christmas present, right?"
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
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