The hassle.
Find it
List it.
Remember someone wants it
Package it.
Send it.
Forget again.
Remember to take it out of the bag.
Give to the wife.
Leaves it in car.
Eventually it gets sent.
And no ody want any of my 9sp XT cassette hoard, as it no mans land.
Not old, not new.
May as well buy a cheapo SRAM or no name one.
And you never know when you'll need that steerer or that bike that been in the shed for 15years and is probs still muddy after the last ride.
Easier to take bits to events or locals if you can.