Just going to put this here: BJJ has influences from yoga, calistenics and diets as well as surf culture.

For a more complete and less biased view, here's the actual wikipedia article.
https://en.wikipedia.org/[...]_jiu-jitsu.

Even when a kodokan or sambo practicioner comes in they mark the BJJ start date when they stepped into a BJJ gym or were deliberately learning BJJ. Did you ever in your olympic career think that you were doing BJJ? No.

Also why do you care so much?

I have trained with judoka basically since I also started BJJ. Even have competed in Judo a few times. Yet, in Judochecker I put the start date at when I first went to Judo to improve my Judo, not to improve my BJJ or MMA which happened more than 15 years earlier.