Did I misread that all facebook/instagram users will have a Threads account by default?
Threads is powered by Instagram, so right now it’s just one account, but we’re looking into a way to delete your Threads account separately.
Maybe I have really poor reading comprehension, but this does seem to imply that your threads account IS your instagram account
You use an Instagram account to register a Threads account, but they are two different services. After the Threads account is linked, there is however no way to remove that account without also removing the Instagram account.
Just for comparison, there are something like 2.3 BILLION Instagram accounts.