Comment by avidiax

The problem domain is that you want to separately encrypt/decrypt various 32-bit serial numbers.

CTR mode turns this into just an XOR operation. That provides very little security. Anyone observing sequential sequence numbers (particularly rollovers) will quickly derive the partial value of the first CTR mode cipher block.

A 32-bit cipher, on the other hand, essentially creates a permutation of the entire 32-bit space that's reversible with the key. Ideally, the encrypted value of serial #1 tells you nothing about the value of serial #2, which is the case for practical 32-bit ciphers.