"Think back, who was the last character you can remember who was given a test run in a limited series and then graduated to an ongoing title?" What about the Maddrox mini? Didn't that lead to X-Factor? Sure, it wasn't a Maddrox solo on-going, but the idea that a mini can lead to an on-going isn't THAT ancient.
Somebody else suggested X-23 as another example. So sure, it’s possible. But not prevalent.