Source

From 1991-1995 (back in the days when he kind of looked like Michael Bay) Steve Austin was actually a member of WCW. The beginning of the end of Austin's reign in the now-defunct league began when he tore his triceps on a tour through Japan in 1995. Afterward WCW's Vice President Eric Bischoff fired Austin saying that he was difficult to work with and wasn't “a marketable wrestler.”

That type of reasoning is pretty much why there's no longer a WCW.