Repeatedly stating something as fact does not make it so.
Not in the context of a debate, of course, but in the realm of propaganda, repetition is a powerful tool.
Is there anything other than your statement to back this up?
That the 3d6 bell curve still represents the general population? There are some facts consistent with it. Quite apart from it being the case in the classic game, and it never being replaced by anything else.
For instance the structure of stat bonuses, with 0 at the 3d6 average of 10-11.
I don't care what previous editions said or did not say, they are no more relevant to the current edition than the tradition of paladins only being lawful good or there only being alignments of Law and Chaos.
Each of those things is relevant. And, again, focusing on the 'only' is missing the point. Law & Chaos are back as an independent axis in 5e. The Paladin in the SRD is the LG Paladin.
The editions of the fad years, the red box and 1e AD&D, are probably most relevant, though.
. But there is no "holy text", there were no sacred stone tablets inscribed with the 15 10 commandments of The Great Gygax.
There may well be, in that metaphorical sense.
They pulled certain aspects of previous editions into the current edition where it made sense
Where it made sense for their goals, which included fast combat and classic feel - and really, a number of other things that all boiled down to classic feel, as well...
. Rolling for ability scores for every NPC didn't make the cut.
Except it did, it just remains an option, rather than a default.