I'm 95% sure that the author (who is on HN[1]) is at least referring to the article "There's No Such Thing As A Tree" in his line "There is no such thing as a tree." - regardless of the fact that the article as a whole isn't about trees made of wood.
It's possible that he's additionally making a double entendre about abstract tree structures.
It's possible that he's additionally making a double entendre about abstract tree structures.
[1] https://news.ycombinator.com/user?id=hwayne