It’s essential, though the Bullet Journal spells out nice, thoughtful, and adaptable techniques. https://bulletjournal.com/pages/book
The reviews have caught hundreds of important ideas and tasks that had slipped my mind.
For what? Many people do fine and much better than fine without.
Why do people come out of the woodwork and act like jerks every time a notes post comes up?
Why waste the energy? If you don’t get value from taking notes, just move along to the next post.
Yet, given that people are both massively productive with and without these systems, it really calls into question the effusive marketing and community promotion of these tools.
I use obsidian everyday, but I recognize that I could do just as well with some other tool. It's preferential, not essential.
Exaggeration is not necessary for communication of value.
FWIW I keep checking in on the Bullet Journal blog once a year or so to get some ideas, but I started keeping a variant of Bullet Journal about 5 years ago.
It's definitely been useful for not forgetting upcoming events, reflecting on the last month and for tracking trends on events in my life (e.g. sporadic food logging when making more of an effort to lose weight). One of the most positive outcomes was from recording key details about events - e.g. if I've met someone new at a language exchange, jot down their name and a detail or two about them. I found just re-reading these notes a day before I'm likely to encounter someone again has massively helped the next interaction because I'm not just going "Oh, what's your name again?"