As it happens, I have about nine users who have been using Jira Software (under the old pre-Core division) for quite some time. They are now on Jira Software.
I also have a fifty-user license for Core, obtained recently, to which I intend to add the rest of the company for strictly business issue management.
However, when adding a user to Core, despite not having Software or Helpdesk selected, it insists that I have attempted to add the user to the other apps.
Forgive me for pointing this out, but I don't think this is an uncommon circumstance. Certainly it is one that should have been anticipated in your user stories. Is it not blatantly obvious that you might have people with low-user-count software and IT licenses, which might be full? And that the "Core" product you're trying to push into business use would then have larger user counts, to which admins would want to add/remove users without bothering the more limited licenses?
Perhaps I'm mistaken, but it doesn't seem like a brainiac would have been needed to anticipate this.

I find this sort of dumbassery really unappealing, especially in software that is over ten years old. What fool programmed this? And how do we get this settled?
I would say "thank you", but I consider this a bug with a very high Borked rating, which should never have escaped into the wild. As such, thanks would be inappropriate.
Please advise.
T