What's so special about playing the piano? In the present context, I mean! I do not see how devoting hours to practising piano is any more or less of a loneliness inducing experience than practising cello, oboe or any other instrument or spending one's time in singing practice. One might argue that composition is an even lonelier occupation in that, at least when one practises an instrument or practises singing, one "communes" with the sounds that one produces whereas, with composition, those sounds remain confined to the head of the composer and do nothing for anyone else until they are performed.
That said, the fundamental difference between loneliness and solitariness has not yet been fully recognised here.
Best,
Alistair