> An archive of files and directories is in itself not a program.

Okay, but you can make the same argument to say that ELF files aren't programs in and of themselves either. In fact, some ELF files are dynamic libraries without an entrypoint, and therefore not actually executable in any meaningful way unless connected to yet another program.

If you can accept that some ELF files are executables and some aren't, then you can also accept that some CPIOs are executables and some aren't. What's the difference between ld.so unpacking an ELF file into RAM and running its entrypoint, and the Linux kernel unpacking an initramfs into RAM and running its entrypoint?