> Who needs libc

This program does, for multiple things, regardless of how the entry point works.

No program needs libc. Most could use it, though.

This program uses for example printf, which is provided by libc, so it needs some form of libc to run.

It’s easy to swap out the limited use of printed in this program, which just prints strings and integers, with a short loop and a syscall. Like I said, nobody needs libc; it’s just convenient to use.

This program, as it is written, needs libc to run. It would not run without a libc.

If you wrote a different program, that didn't use libc, then it would not need libc, that is correct. But would that program fit on a post card?

That’s my argument: it probably could; I think it would be a dozen or so more characters.

Even the AMD64 instruction names alone for fabsf, sqrtf, powf, fmodf, will add up to more than a dozen characters. That's before you implement rand and printf. I'm skeptical.