Why not? The author of the post wanted to point to a specific part of the terms. How would they do it otherwise?
Lots of past explanations here:
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so...
In practice, there's a grey area - see my recent post here: https://news.ycombinator.com/item?id=43179132 (specifically the 3rd and 4th paragraphs).