Not entirely correct.
The writing was on the wall for piston engined aircraft, especially fighters. Look at the amount of kit, of all types, that was dumped at the end of WW2, especially in the Far East.
P40s, location unknown.
B24s
A heap of P38s, ready for burial at Clark Field in the Phillipines. These are still buried, they're beneath the power station site, so aren't going to be enearthed in the foreseeable future, despite the best efforts of some rather rich Americans!
The cost of bringing these planes back to the UK/USA, where they would only be scrapped anyway, was more than their value. Reload onto trucks/railways, offload at docks, reload onto ships, sail back to the UK, offload, truck/train to disposal point, add to the thousands of Allied & Axis planes, all awaiting scrapping. Remember that the Yanks couldn't be bothered to ship back to the US half of the planes they'd sent to Europe, including brand new ones!
Also, they weren't "state of the art", Spitfire XIVs had been superceded by the Mk21, 22 & 24, it's more like thinking along the line that they were Tornado GR1, so not even upto GR4 standard.
It also gave the thousands of men, waiting to be shipped home & demobbed, something to do!
Some planes were sold/given to the newly liberated countries of the CBI theatre, Spitfires to Burma, for instance, but there's only so many they'd need and the Yanks would be as keen to offload Mustangs as we'd be to get shut of obsolete Spitfires.