This has been happening a fair amount recently, and it's really annoying. Another example — https://news.ycombinator.com/item?id=4933472 — was when the HN editor changed the submitted title from "Why I Won't Relocate to Work for Your Startup" to "Why I Love Being A Programmer in Louisville" ... the title of the blog post was, in full, "Why I Love Being A Programmer in Louisville (or, Why I Won't Relocate to Work for Your Startup)", but the part that was relevant to the HN community was the part about not wanting to relocate (not anything in particular about Louisville).

I don't know why people at HN (pg? someone else?) are applying such a heavy hand to the title editing, but it's getting tiring. Perhaps there are good counter-examples, where they've made links more on-point by changing them (I'd be interested to see them if anyone has them), but the posts that stand out in my mind have been made both less relevant and less interesting thanks to editing by someone at HN.