First I gotta say that following or believing whatever somebody says, just because that person is holding a high rank is stupid.
There's a reason why people talk about WTF-Taekwondo and why people talk about Taekwondo being 2000 years old. It's the instructors, masters and grandmasters who pass this on to those who train under them. Those who're lucky to find instructors who would go more into detail or those people who do some research will get to learn about the role of WTF, Kukkiwon, KTA and other national member organizations.
I don't really see a problem wih people talking about WTF Taekwondo being their style of Taekwondo since WTF and Kukkiwon used to be and still are pretty close. In the early days of the Kukkiwon the WTF secretariat was located in the Kukkiwon. Plus Dr. Kim Un-Yong was president of the WTF, Kukkiwon and KTA.
View attachment 19073
Whenever somebody would ask me what style of TKD I train I'd always say Kukkiwon though. ;-)
And while the WTF is just the governing body that's taking care of the sport-side of Taekwondo they issued Poomsae books in the past though:
View attachment 19074
View attachment 19075
This doesn't help to identify the style of Taekwondo that somebody's practising as Kukkiwon Taekwondo, either.
And then on top of that a lot of the national member organisations of the WTF issue their own Dan certifications and even called the Kukkiwon Dan "WTF Dan" for many years. Actually some may still call it WTF Dan.