Neonchameleon
Legend
When I google the first hit I get is Reddit asking how to balance rolled stats. The second is a thread during the playtest suggesting how to balance rolled stats. The third is Stackexchange asking how to balance rolled stats.Please, do look it up.
I see absolutely no evidence from looking it up that the game is balanced round rolled stats.
I see evidence that rolled stats are the first option listed in the PHB - but absolutely no evidence at all that that's how the game was balanced - merely that it was a way of appealing to a certain audience to whom balance was frequently a dirty word. I further think that if they thought that "+2 to one stat us worth the same amount as +2 to another" either that was pure sales or they were higher than kites.
In short I have looked it up. I have found nothing. If you have the link to hand I would be delighted to see it. But the idea that all else being equal +2 dex is worth the same as +2 Int in D&D is something that I believe came entirely from you - and my trying to look it up has only confirmed this. (And if they did say it then that reflects more on them as game designers than it does on reality).