Some components that have been proposed to be admitted to the C++ standard were also contributed to Boost, but that's about it. There are far more components in Boost that were never even considered for the standard than the ones that were.

Nevertheless, the relevant part is that Boost is not nor it ever was C++, or representative of C++. Conflating third-party libraries and frameworks with the C++ programming language is at best a pointless straw man.