> Google was saying "from day one" it was a literal showstopper,

For a long time people on the C++ standards committee insisted that we need trigraphs because it had to support systems that didn't even have ASCII. We still don't have pragma once as a standard replacement for include guards because other people seem to compile on some crazy network typologies where it cannot reliably identify files. Taking every "literal showstopper" serious without questioning its merits gets you stuck with C++98 and a lot of quickly accumulating legacy cruft.