People keep saying crap like this but Blizzard is known for being full of old timers. That’s basically it’s industry reputation.
Just for WoW:
Ion Hazzikostas - Game Director: 11 years at Blizz.
John Hight - Production Director: 7 years at Blizz.
Chris Robinson - Art Director: 13 years at Blizz.
Alex Afrasiabi - Creative Director: 15 years at Blizz.
Patrick Dawson - Technical Director: 15 years at Blizz.
Steve Aguilar - Lead Animator: 15 years at Blizz.
Dusty Nolting - Lead Animator: 9 years at Blizz.
Ely Cannon - Lead Environment Artist: 11 years at Blizz.
Dan Moore - Lead Prop Artist: 21 years at Blizz.
Matt Goss - Lead Game Designer: 9 years at Blizz. (This one is hard to tell)
Morgan Day - Lead Encounter Designer: 12 years at Blizz.
James Chadwick - Lead Level Designer: 19 years at Blizz.
Russell Petersen - Lead Rewards Designer: 11 years at Blizz.
Eric Maloof - Lead Quest Designer: 16 years at Blizz.
And most of these people have spent nearly all of that time ON WORLD OF WARCRAFT ITSELF.