The logic of tank destroyers is easy to understand. They are, essentially a much more mobile version of the towed anti tank gun. And they are very effective when used as such. Tank destroyers are meant to kill tanks, not fight tanks.
The trouble is that they look like tanks. And people tend to think of them AS tanks, and try to use them, as tanks. And for that, they have serious drawbacks.
There were two basic styles of tank destroyers during WWII. A tank killing gun on a halftrack/full track chassis with light armor, (and often open top), and fully armored ones mounting heavier guns than comparable tanks. Usually turretless. Germany and the Soviet Union made extensive use of the assault gun/tank destroyer types.
The US TD (after we got past using halftracks) had turrets. Light armor, but fully rotating turrets, so they looked exactly like tanks to everyone except the TD crews and commanders. This often lead to them being ordered into ..inappropriate roles and situations, where they didn't come off so well.
but every nation has done this, officers not understanding the best use of particular weapons (especially when they are new systems), and because of that, throwing away their advantages.
Such a thing is (perhaps) forgivable when something new is first deployed, (The Germans lost all the first few Tiger tanks they used, because while the crews had learned what you could, and couldn't do with them, the field commanders giving the orders had not, and sent then into swampy forest where they were very restricted to movement, and easily got stuck) but after that, using the wrong tank, plane, etc for the mission is just pig headed ignorance, something which ALL militaries have in abundance.