He’s the classic example of fake it till you make it in modern America. A guy who makes flashy viral videos, has zero actual experience of leading organizations or teams, yet someone has acquired some guru like reputation at a genius leader.
Still, a great example of marketing and proof that fluff sells and is probably useful for many.
Taking him at his word on several of his talks, he leads a team right now. Presumably one focused on advancing your second point: his marketing of himself.
> His advice doesn’t say anything new and is usually extremely banal.
The corollary being they’re banal to you, cue tangential XKCD: https://www.xkcd.com/1053/
Note I’m not necessarily disagreeing with you. He also seems to me like someone who teaches what he learned by theory, not practice. However, I do believe his intentions are genuine, that he wants to make the workplace better for everyone, and that his points are actionable and positive. Contrast that to someone like Tony Robbins, which I view as little more than a scammer that wants to trick you into thinking anyone can be successful at anything if they just believe in themselves and pay him hefty sums to attend his seminars.
I've read well and deeply across a broad spectrum of classic philosophy and psychology and I think Simon Sinek is a dilettante and basic thinker. I'm allowed to have that opinion regardless of whether I have written books or not.