You can do that sending while you're waiting for the disk to provide said GiBs. I also believe that useless uses of cat are often acceptable for readability (many novices are not familiar with redirecting standard input, particularly not as the first thing on a command line).
Who said the GiBs need to be fetched from disk; they could already be in RAM. Even if not, it's still adding many system calls and context switches when the CPU could be doing other things; the machine isn't running just this one thing.
