What you are saying is that it is possible in theory, but no one has done it yet. So in some future were someone rewrites all C++ compilers to not be so slow then we won't need to compromise.
Most C++ devs have to work with tools that currently exist and so we are stuck with what the compiler devs give us. Believe it or not C++ compiler devs are pretty smart people and have largely optimized it as much as possible without a language redesign.
That language redesign is in the works with modules, but the dust hasn't settled yet, so that is also a discussion for the future. In the mean time no other language delivers the performance C++ does right now. So if I want to ship product right now the very real dilemma is fast product with slow builds (and a bunch of tools for dealing with that) with C++ or use some other language for a faster compiler and a slower product.
Then there is Rust, but that is another whole can of worms and not in use in most shops yet (Just switching to something has a huge cost).
C++ is a language that's incredibly hard to compile efficiently and incrementally, because it suffers from header file explosion (among other things) and as you mentioned it has no working module system.
C compiles a _lot_ faster than C++, so that's always an option. And as other people have pointed out, you can get C++ code to compile much more quickly by being very disciplined about what features you use and how your code is laid out.
So I agree that if you want to ship something right now all your options have significant downsides. I think software engineers as an industry don't take tooling nearly as seriously as they should. Tools are performance amplifiers and we currently waste a staggering number of manhours working with poorly designed, unreliable, poorly documented and agonizingly slow tools.
Most C++ devs have to work with tools that currently exist and so we are stuck with what the compiler devs give us. Believe it or not C++ compiler devs are pretty smart people and have largely optimized it as much as possible without a language redesign.
That language redesign is in the works with modules, but the dust hasn't settled yet, so that is also a discussion for the future. In the mean time no other language delivers the performance C++ does right now. So if I want to ship product right now the very real dilemma is fast product with slow builds (and a bunch of tools for dealing with that) with C++ or use some other language for a faster compiler and a slower product.
Then there is Rust, but that is another whole can of worms and not in use in most shops yet (Just switching to something has a huge cost).