In addition to the sibling comments, I'd point out that the article is sort of an extended riff on the phrase, "There is no such thing as a fish," which was a sloppy QI paraphrase [0][1] of a principle elucidated by the 20th century paleontologist Stephen Jay Gould, and later became the title of QI's well-known podcast [2]. And of course, fish do exist, just not in the simplistic way that many of us were taught as children, that they are one of five genetically discrete, self-contained, non-overlapping taxonomic classes: Fish, Amphibians, Reptiles, Birds and Mammals.
The author is arguing that if you are going to say that about fish, you can say it about trees, fruit, and plenty of other things. That may be true, but unlike with fish, I don't ever recall being given the impression that trees and fruit were genetically discrete self-contained scientific categories. Fruit just seemed like something that some plants have, without any sense that fruity plants were necessarily more closely related than non-fruity plants. I mean, "biped" is also a category but nobody ever claimed that birds and humans are genetically discrete from the other four, six, eight, etc. legged animals. Still, it's a fun and interesting conversation, even though the author may have been forcing the fish analogy a bit.
[0] QI ("Quite Interesting") is a long-running British trivia/humor related game show
The point seems to be close to what you describe, but not entirely: "chair" is a human-made label, assigned to physical objects in the real world, but it's too abstract. Lots of objects resembling a chair or named "chair" exist, each with their own peculiarities, features, identity, but that's just humans going around, marking stuff with an invisible label maker.
The author is arguing that if you are going to say that about fish, you can say it about trees, fruit, and plenty of other things. That may be true, but unlike with fish, I don't ever recall being given the impression that trees and fruit were genetically discrete self-contained scientific categories. Fruit just seemed like something that some plants have, without any sense that fruity plants were necessarily more closely related than non-fruity plants. I mean, "biped" is also a category but nobody ever claimed that birds and humans are genetically discrete from the other four, six, eight, etc. legged animals. Still, it's a fun and interesting conversation, even though the author may have been forcing the fish analogy a bit.
[0] QI ("Quite Interesting") is a long-running British trivia/humor related game show
[1] https://www.youtube.com/watch?v=uhwcEvMJz1Y
[2] https://www.nosuchthingasafish.com/