I have seen it, I think it's because it's not easy to see whether the cmdlets or functions your calling support and support it right. It does work, but I have seen it not always work and that results in having to check or test every command. I think the GP is overstating the incovenience, though, and Powershell is still much, much better than any Unix shell in this respect (which simply has no mechanism and no standard way to discover one).