There is a lot of truth to this, and it in some areas the situation is far worse than even this article discusses.
A couple of nuances first. The low rate production of things like cruise missiles, smart munitions and the like is not only because they are expensive, but also because it is critical to keep those production lines open. The government and industry try to strike a balance where industries' fiduciary responsibilities to its stock holders and the genuine desire of a corporation like Lockheed or Northrop Grumman to make business decisions that are in the best interests of the country. Slow but steady production keeps the assembly line hot and keeps costs manageable. Cheapest would be one time huge orders, but the assembly lines would go cold immediately afterwards. Restart would be more than merely challenging.
Tracked armored vehicles are another example. We have one tank factory and two capable of building armored fighting vehicles and artillery. I think we can all agree that is not healthy should a major war break out. The problem is the complexity of these vehicles. They have far more in common with an attack helicopter or small combat vessel than their predecessors of the Second World War. Because of that, Ford or GM can't can't simply retool and start churning out Abrams MBTs like they could Shermans in 1942. I should further add, the US has not put a new tank or tracked armored fighting vehicle into production since the 1980's. That no-how is being maintained on something close to life support by BAE rehabbing and updating the Bradley and GD doing the same with the M1.
One delay with regard to Stinger is that many components no longer exist. Much of it will have to be redesigned.
So yes, maintaining stockpiles and hot production lines is an incredible challenge. Due to the complexity and expense of those products, I see little relief regardless of lessons learned in Ukraine.