The conjecture is this: The people that took over around 2005 were fundamentally the ones in the category who stood up and said, "I don't like D&D, any of it, from 1975-2005".
Andy Collins - Worked at TSR since 1998. Credited with additional design and contribution on the 3e core books. Tons of 3e credits from 2000 onward, including involvement in 3.5.
Rob Heinsoo - Worked with WotC since 2000. Credited with design contribution and editorial assistance on the 3e core books. A few 3e credits from 2000 onward, including involvement in 3.5.
James Wyatt - Worked with WotC since 2000. Credited with design contribution on the 3e core books. Tons of 3e credits from 2000 onward, including involvement in 3.5.
Mike Mearls - Worked with WotC since 2005. Before that, he has credits on a vast amount of d20 products, many of which received much acclaim from the d20 community.
Rich Baker - Worked with TSR since 1992. Credited with more contributions to D&D than you can shake a +1 stick at.
Bill Slavicsek - Worked with TSR since 1988. Tons of credits in D&D products, including being Director of RPG R&D during the development of 3e.
So yeah, this whole "2005 takeover" nonsense has what... one guy that was hired around that time, with all the rest having been a part of D&D development since the inception of 3rd Edition (or earlier). This conjecture is certainly not based on the history of these people's careers in the industry, and especially not their actual time developing D&D. I'm sorry, but this claim that they all spent years (decades in some cases) developing games they don't like is really silly, since you're essentially saying that they hate their own work.