I don't think it's that shocking because the writer is probably going off their own experience of co-operative play. I do concede that the meaning of co-op in certain contexts can vary quite some-what, for example, if we are talking options i.e. multi-player, story and split-screen as an overall package then yes this list could be contested.
They should of just made a top 10.
but yeah, if i made this list atleast 2/3, maybe 3/3 of those games would be there
L4D1+2 is on every co-op list but fails to make it here?