PBL by its very nature hands more control to the vendors (which is always the other party), in return for a stipulated and contracted service level, availability, and cost. Alternative is to build and manage your store inventory yourself, which can get expensive when the government is doing it, not to mention the uncertainty of annual funding and delayed budgets and just the overall inefficiency. This is why PBL's are so popular the world over. Skinny PBL's work too and the US Navy has successfully done that on its strike fighters. Whatever it is, will always be a partnership so some control has to be given to the vendors who are contractually agreeing to it (otherwise why would they sign up). Technical baselines can be owned by the government but you have to buy them and then be able to do something with what you've bought. I saw the entire hearing, nothing in it was surprising. The JPO had been providing data to the services, and the USAF, during budget crunch of the past, has prioritized procurement over sustainment. Congress on the other hand has refused to retire aircraft at the cadence the USAF has requested which leads to problems with getting enough maintainers freed up, and trained on a new platform. All of this will continue to be an issue until they get their depots stood up and right sized for the fleet (and growth). It is a lesser issue with international customers because those have had the option to be on a PBL for a while now, and many are already using it to manage their fleets.
The USAF declared IOC on the F-35A around mid 2016. Yet, by late 2015/ early 2016 their F135 engine depot barely had the capacity to overhaul modules even though it was supporting the entire test fleet, training fleet, and the operational units that had begun to get equipped with new aircraft. This was fine as long as the production rate was in the 40-60 range as the engine production could be ramped to have an inventory of new modules available as the turn around times for repairs was in the 200+ day range at the depot. But now the production rate is in the 150 range and there is little surplus capability from the engine OEM so they have to improve their depot turn around time. So they were slow to stand up, and were slow to expand and are now lining up double shifts, and what not to catch up. The investments that they have made, and have promised to make will right size their engine depots by about 2025-2026. It's not an easy fix because they neglected these investments in the past so it will be a slow recovery. But because break rates elsewhere (mission systems etc) are better than expected, they will still continue to get or exceed 70% F-35A capability rate and be able to meet their deployment obligations. The biggest problem is that not only does the engine depot need to get going to clear backlogs, the fleet continues to grow. by end of 2024 the USAF will have more than 500 operational F-35A's, and the Navy and USMC inventories would have also increased (USN would have more than 100 operational F-35C's ).
What the USAF needs to do is build up an intermediate depot capacity which they completely did away given the budget outlook in the post 2010 sequester years. They have to build this back up before the fleet gets to a 1000 aircraft and you have the first engine modules reach their 2000 hr overhaul. To get there, they probably need to divest some of their older aircraft which are nearing the end of their life. They consume a lot of resources to keep up in the air and that manpower is going to be needed on the flight line and in running these new facilities along with the civilian workforce.
What the USAF needs is a complete overhaul from the ground up just like was done during the Reagan build up when the 4th generation fleet was purchased. New aircraft, retiring of older aircraft, and creation of new, and upgrades to existing, depot and overhaul facilities to support a larger 5th generation fleet, and the upcoming 6th generation fleet. Given budget realities however, the USAF has had to stagger these, focusing on procurement when budgets were tight and addressing sustainment in subsequent budgets.