It all started with the US DoD decision to save money by using a common platform for three services and three different missions. It will all end with none of the mission capabilities being achieved to the degree possible with three independent different designed platforms. Even the decision to save money hasn't panned out and never will except by accounting manipulations. A study of history and lessons learned from previous experiences were dismissed as not applicable in the F-35 decision making process.
So who's to blame? Both the customer, who demanded it be done and the suppliers who really didn't know how to oblige the customer's demands, but pretended it could be done, "Yes sir, we can do that!" So was the problem a result because of changes in requirements once the program left the starting gate? Hardly, if anything, favorable moving of the goal posts as insurmountable technical issues were encountered provided respite. And yes, you can blame more than just L-M, the US Congress, P&W, the software producers and the magic helmet suppliers can all be held accountable for a program that is years late. Does anyone understand what it means when technological advantages are lost when a program is as late coming to market such as the F-35? Geez! Even the JPO Leader General Bogdan now sees the mistakes and has advised appropriately for future platforms yet to be designed.
CM, You may think it would be worse if more countries had been co-program leaders such as the Typhoon program. Nevertheless, for the F-35, the UK will bear the increased acquisition costs, life of aircraft costs and performance shortfalls as if they would have been a co-leader, sometimes it makes no difference or maybe even be worse. Think of it this way, the US had 49 participating States as co-program leaders, far more than the Typhoon program and less pragmatic.