this is still the state’s fault. 
here’s a similar case: pharmaceutical companies get a patent for a new drug that will last for x years, and acting in their own self-interest they exploit the fact that they can extend the patent with minor modifications to the drug. 
it’s a drug that could easily be produced at a low-cost by competitors. 

as you’ve noted, the state doesn’t force them to extend their patents, but there’s a clear incentive for them to do this. yet in a free-market, this is not possible and competitors would make the drug.
capitalism fixes this, but the state creates the problem.