That's my thought as well. It probably would be even worse. For instance it possible to write a leaf function in assembly for AMD64 that runs both on linux and

That's my thought as well. It probably would be even worse. For instance it possible to write a leaf function in assembly for AMD64 that runs both on linux and windows if all you do is return a value. This is because they both use RAX as the return register. There subtle difference between the two but that is mainly what registers are used. The biggest difference comes in the stack layout. Now when it comes to pretty much any other OS for instance on x64 they pretty much use the System V calling convention. The thing is if C was not the glue, I could imagine the ABI would be wildly different on each OS heck maybe even each version of the OS. If we look at windows you can't safely call any system calls directly since a major update could change the system call number. However, windows provides wrappers around these system calls. Linux is an outlier in OSes that considers changing system calls like this as breaking user-space. Now if we did not have C what would operating systems be using to wrap all these system calls? I suspect something tailored to that OS specifically and it would be quite the mess so I bet it would even be worse to handle. Since at least C keeps things similar. Whereas without it you would get OS specific schemes that could vary by a lot more! Making the code base to support multiple platforms even larger.