No, it isn't. modprobe has a configuration file, and one of the directives in the configuration file is "if asked to load this module, run this command instead"

No, it isn't. modprobe has a configuration file, and one of the directives in the configuration file is "if asked to load this module, run this command instead". And that command is sometimes "go figure out which module to really load". So "running modprobe running a shell running modprobe" was correct.