No one company has owned D&D this century. Most of it is in the public domain (Open Game Content), with some fiddly details restricted. For a while Hasbro's latest D&D was selling less than Paizo's, although I think Hasbro regained the lead. And even in the 1990s, you could share your own house rules, monsters, spells, etc. as much as you liked as long as you did not try to make money from them. RPG designers have very little control over what people do when they sit down at the table.

If the author thinks that the latest version of D&D published by the biggest corporation is the 'real' one, that just shows that he has adopted the corporate ideas he claims to reject.