Text says: "it would be given some number of filenames as command line arguments, and it would read those ... Options didn’t exist".
Example shows: unneeded usage of `cat` as if `wc` is non-standard utility and cannot process file names by itself, option for `wc` is used. It contradicts text in both ways!
Are several memory copies and context switches free for you? They are most expensive operations on modern hardware (yes, I know about splice syscall in Linux, but it is Linux-specific and don't avoid context switches).
I think, on very high-end modern storage subsystem (like, stripe built out of several enterprise-grade NMVe SSDs) impact will be well-measurable in case of simple "wc".
Text says: "it would be given some number of filenames as command line arguments, and it would read those ... Options didn’t exist".
Example shows: unneeded usage of `cat` as if `wc` is non-standard utility and cannot process file names by itself, option for `wc` is used. It contradicts text in both ways!