I have two Apple accounts (IDs). One is primary and my devices are signed in to it. The other is secondary and was used for most app and music purchases. I used the (relatively new?) account migration process to move all purchases to my primary account, with the intention of then deleting the secondary account. The migration seems to have succeeded and left the secondary account empty. However, in starting the account deletion process (logged into privacy.apple.com as the secondary account), one paragraph under "Important things to know before deleting your account:" reads:
"Purchases have been migrated from this account to another account.
Deleting this account will undo migration of purchases made with this account"
What? After migrating you cannot delete the account that originally made the purchases? Doesn't seem logical.