That seems like it'd get really awkward pretty quickly. "if" isn't unique in this regard; there are about a hundred shell builtins, and all of them can be used

That seems like it'd get really awkward pretty quickly. "if" isn't unique in this regard; there are about a hundred shell builtins, and all of them can be used as an argument to a command. (For example, "echo then complete command while true history" is a valid shell command consisting entirely of names of builtins, and the only keyword in it is the leading "echo".)