"Orthodox C++" without templates, language features, or the standard library is also known as "C".
I'd go one step further. Skip the compiler and just write in assembly. Your builds will be lightning fast especially if you use one single source file with no macros and static linking. You'll never ship, but you'll never ship really fast.
Except people do in fact ship large C projects all the time. The productivity gain associated with moving from assembly to C is undisputed and vastly exceeds any alleged productivity gain associated with moving from C to modern C++. Pretending otherwise is just facetious.
Or anywhere else. C++ is such a beast, you just can't expect your coworkers to memorize the whole standard, so it is quite common that teams agree (or the team-leader agrees for them) upon a subset.
In the past that was due to limited availability of experienced C++ programmers and inconsistent support from compilers, these days it's due to the evolving nature of the language. Quick: in which standard was the variant class template introduced?
I'd go one step further. Skip the compiler and just write in assembly. Your builds will be lightning fast especially if you use one single source file with no macros and static linking. You'll never ship, but you'll never ship really fast.