You are absolutely correct, however I would argue that it has only relatively recently entered the common HN lexicon. The vast majority (~675 out of 704^) of comments using it here in the comments are < 2 yrs old.
Admittedly the first comment on HN that used the term is 7 years old, but that comment [0] predates the creation of the wikipedia article (frequently trotted out when invoking the term here) by about a year.
As an aside, I'd love see a dataviz app that shows the lifecycle of terminology and memes that thrive in various internet discussion boards.
0) https://news.ycombinator.com/item?id=2944345
^well it'll be 705 including this post ;)
Again, that still doesn't make it new or intellectually dishonest to point out.
Not accusing you of the above, but "Whataboutism" is as old as double-standards it draws attention to. But IMHO the accusation is more often use for ill than for good.