> If I wrote some code, I expect it to be present in the binary.

That's oversimplified. If after inlining and constant folding an if-condition turns out to be always true or false I would definitely expect that the compiler removes the dead branch.

This type of optimization is the base for the fabled "zero-cost-abstraction" (which isn't only a C++ thing, C code depends on it just as much), and removing those optimization would seriously tank peformance in any non-trivial codebase.