You're right it does,doesn't it? I think it is simply because so very many dogs don't get much exposure as pups and grossly undersocialized pups can have some pretty tough issues to deal with. In this country Joe Q Dog owner that "can't/won't deal" with dogs with issues tend to do get rid of said dog.
There is also the issue at the other extreme, over- socialization, where a pup is uncomfortable but 'in the name of socialization' he has to atempt to deal with things he isn't ready for.
Again though, so much depends on the 'bounce-back' factor of individual dogs. Heck many 'country raised' dogs do better because they are allowed to deal with stuff at their pace and don't have so much thrown at them at once like a city dog would...