> It should give you the maximum integer available

How would you compile that to machine code which would, when run, still give you the maximum integer on next year’s CPU with all-new super-duper wide integers?

It is more reasonable to think of a binary to be compiled to a specific architecture triplet, and if the CPU changes, the architecture must change, and therefore the ABI, and if the OS wants to run a binary from an older architecture, some emulation layer is needed.

Of course, this would be a lot of work for the operating system people if they want to run binaries from lots of what are now different architectures, and it was apparently easier to just force the C standard to abandon the entire concept of intmax_t being the largest.