MG-42

That's like saying the design of the internal combustion engine was flawed because it would seize-up on you unless you used motor oil!
True, barrel changes were needed, but that was thru operator error. MG crews were trained to fire only in short 7-shot bursts, ( in spite of what you see in the movies ). This was due to the fact that sustained-fire had proved to be inaccurate, and it wasted precious ammunition. Only when MG'ers ignored their training and kept firing and firing and firing did the barrel overheat, requiring it to be swapped out.