Hood liner insulator discussion

[Cobra Jet]

Why did some agencies delete the hood liners?

If an Agency deleted the liner for one model year, did they usually do it across all orders they placed each year after?

Reason I’m asking is looking through many online photos, I’m seeing some SSP’s with deleted hood liners and others with the hood liners. The problem is, I don’t know how it was when the vehicle was in-service since many (at this point in time) the images are of restored examples and it’s possible the civilian owner didn’t reinstall a factory hood liner due to lack of supply (now)….