You seem to be contradicting yourself. You first said you can't use an Apple email for an Apple ID,
For the second time that isn't what I said at all, I said...
You can only change your non-Apple address to another non-Apple address
Which means the non-Apple address you currently have associated with your ID can be changed but only for another non-Apple ID, I didn't even mention an Apple address in my first post.
then you say that you can use an Apple email address, and then in the next sentance say you can't.
You need to re-read what I've written. I'm not sure which sentence you are referring to in my post, but the first sentence in my second post merely points out what I've just said above...
I didn't say you can’t use an Apple address for your ID.
After that I said...
An ID has both an Apple address and a non-Apple address associated with it, you can change the non-Apple address for another non-Apple address, but you can’t change the Apple address at all.
Which is exactly how it is. For example, my Apple ID has the two addresses (not real for example only) winnie @ iCloud.com and winnie @ hotmail.com
I can change the non-Apple address I use for my ID, for example, I can change it from winnie @ hotmail.com to winnie.c @ yahoo.com but I can't change the Apple address I use which will always be winnie @ iCloud.com