I first used C++ around 1990, when it didn't have much of a standard library. Then came the Annotated Reference Manual with its crazy talk of templates and namespaces and what not, which weren't implemented by any compiler I had. Somewhere around here is a copy of PJ Plauger's book on the standard library that doesn't mention templates at all. The standards committee pulled a fast one on Plauger: between the publication of his book and the finalization of the draft, the STL took over the world. Then came C++11, with move constructors, anonymous functions, and a couple of new smart pointers (which was good). C++14 introduced type deduction. And there's Boost's smart pointers (and everything else).

Nothing requires a rewrite, but five year old code looks nothing like what people say is "best practices" now.