The list is so damn long
Former TNA/Impact Talent in WWE:
AJ Styles
Angel Garza
Bobby Roode
Xavier Woods
Cameron Grimes
Dexter Lumis
MSK
Drake Maverick
LA Knight
Santos Escobar
Mark Andrews
Joaquin Wilde
Karrion Kross
Scarlett
Franky Monet
Former ROH talent in WWE:
Cedric Alexander
Damien Priest
Erik & Ivar
Keith Lee
T-Bar
Cesaro
Kevin Owens
Seth Rollins
Sami Zayn
Adam Cole
Bobby Fish
Kyle O’Reilly
Roderick Strong
Tommaso Ciampa
Former Talent from Japan in WWE:
Finn Balor
Shinsuke Nakamura
Ricochet
Io Shirai
Toni Storm
Kushida
Akira Tozawa
Sarray
Asuka
I didn’t even mention PWG, AAA, CMLL, or other various companies, I didn’t even bring up guys like Drew McIntyre, Bobby Lashley, Jeff Hardy, MVP, and Rey Mysterio who were released and made a name for themselves in other companies were then brought back.
I don’t even have an issue with WWE getting these guys if they can use them right, but if you look at the biggest promotions in the US in the past 25 years (WWE, WCW, ECW, TNA, AEW), of the biggest stars, only Cena, Rock, Goldberg, and Reigns were homegrown, everybody else came from somewhere
WWF/E has never been good at developing their own talent. Besides the OVW crew, they just steal wrestlers that other promotions have developed.