The STL was a special case. I will never understand why it took so long for the big vendors to stop using wonky, novel, non-compliant implementations of the STL. The worst offenders where VC++ and IBM's VisualAge, neither of which even bothered to get the string class right. The closest I could get to compliance before I started Linux development was using SGI's implementation on a Borland compiler.
In all my years as a Windows C++ dev, I was never allowed to use the STL because the chances of hidden library changes affecting otherwise dormant code was too great. Old code should be low-risk, and you have to choose your libraries accordingly.