Yeah, I thought the blog post was gonna be about horror stories, because even the greatest senior/architect/whatever will push absolute garbage into your codebase, if they don't have the time to familiarize themselves with how the code actually works.
Even if it's some isolated component, if they implement it without explaining the what and why to others, then no one else can maintain or debug that. And you do not want to rely on your super important guy to have the time to fix things when production grinds to a halt.