I have no idea where you're getting any of this. Do you have an actual reference to back it up? Even if you're correct, I disagree that the game was totally geared towards old school gaming. If it had been, it would be far more lethal, have save or die everywhere, no short rest, etc. Or maybe it would have just been a cleaned up 3.5.
Nowadays 5E has been growing double digits every year, so of course new players outnumber old.
As far as cultural shifts and growth of the game I find it hard to believe that 4e towards the end of its life cycle would not have also benefitted from the same cultural shifts and changes. It didn't.
Don't get me wrong, I think if 4E had not been labeled D&D a fixed up 2nd version (or been given proper development time)could have maintained a sizeable niche. I just don't think it ever could have been as popular as 5e, it simply caters too much to a specific target audience. Nothing wrong with that, I just don't see it as having as broad an appeal. Of course now we'll never know.
I just find it odd that people can't simply accept that the game is actually pretty good. The authors put out a decent product. There doesn't have to be this "it's practically a minor miracle 5e is successful".