I often wonder when supermusicians go recording with other supermusicians. Lionel Ritchie went off to record with today's new Country Musicians. Of course at the time, apparently Ritchie did owe some heavy taxes.
It seems this is always merely a "boost-my-record-sales ploy". Sometimes during their early career, they would'nt be caught dead sharing the spotlight. And, they generally record with the younger and popular musicians.