A sliding scale wouldn't be so bad if it were consistent. The problem is that it keeps changing on the modern side, while staying "frozen" for the Golden Age, meaning that the gap between events gets further and further apart.
The writers at DC seem unwilling, or unable, to accept that the Justice Society members would be in their eighties or even nineties by now. And, while I recognize that they've played games over the years with limbo and other things to retard the aging process, at some point it just becomes too unwieldly.
I think you have a growing similar problem at Marvel with Captain America. While I realize that he was in suspended animation, as WWII recedes further and further into the past it becomes more and more unbelievable that modern day Americans would even remember who he was when he gets thawed out.
