I'm surprised this isn't already a question, but I couldn't find it.
When you create a "global" profile for SE sites, like the one you're supposed to link to for your personal site, e.g.
you can only copy one of your other profiles. Well, that isn't really helpful, since one might get pretty specific about why you are on that particular site (Stack Overflow, Academia, Sci-fi, Linguistics) and none might be very helpful.
I guess that in some sense this is a feature request, but for now let's just say it's a question for why this decision was made. Note: this is not a dup of this question.