I doubt the Wizards put any pressure regarding this on Larian. Sincerely. They're rarely worried about this sort of thing, it's for them - way more of an advertisement than anything else. Many games under the D&D banner only very loosely adhere to actual ruleset. When BG2 came out, 3E was already there, too. Of course, that was TSR, still.
And even still, this OneDnD thing - gods I hate that name - is hardly different from 5E from what I understand. A little too much with the inspiration thing, but I'd homebrew that right out of there.
