It was inevitable, with the recent situation with The Smiler filtering to sister parks and many years of questionable service it was a mere waiting game before the park's suffered enough to cause this.
Merlin have had a hold of the 4 parks for almost 10 years, 10 years of poorly made decisions, poorly executed projects, questionable service and availability. One day service may well be top quality, but many other days the service would be enough to make the devil look a saint.
With all of the above, I'm surprised this didn't happen many years ago.