By adding a small bit of human text, the human doesn't have to ponder the list and wonder what they will get if they click a link.
And if there were human text, someone arriving by way of the parent comment link would have an easy time understanding the context without having to scan a lot of characters and make assumptions.
The comment they replied to literally said "Let's take a second to remember that copyright is the reason ~every child doesn't have access to ~every book ever written."
What? No. An ad hominem is "I think your argument is wrong because your face is stupid". "This is bad software because it looks like it's made by amateurs" isn't attacking their character, it's attacking their ability to write good software, which is highly relevant.
"The code is bad because it was written by a novice dev" sounds like an ad hominem attack to me (as opposed to "the code is bad because of X attribute of the code itself").
A lot of people are getting really hung up on this. "Modern Rust" is just current Rust. Once Rust moves on, that will be modern Rust and what we once called modern will no longer be modern. Like all things. You might as well get upset that somebody said something will happen "tomorrow" because in 24 hours it won't be "tomorrow" anymore.