User blog comment:LatteRumor1/Why Matrix should not have been erased from the continuity/@comment-3361105-20120618222501

Matrix was pretty cool, but she was completely different from the supergirl that came before. As such, she wasn't considered officially to be supergirl - from either a canon or editorial standpoint. Her book wasn't doing that well, either. It had a bit of a cult following, but it was nowhere near as successful as Supergirl Vol 5 was. That supergirl was the first time fans of the original supergirl weren't let down by news that their supergirl wasn't the REAL supergirl.

But now, so many people have been erased from continuity that the loss of matrix is pretty insignificant in comparison.