It only talks about customer pricing and there is a lot more to it than that. On overly nice founder might have trouble of disposing of a bad employee, which could destroy the culture or destroy the product. They might accept worse investment terms by being nice to investors which might allow themselves to be removed.

So, in terms of not overpricing the product, there is a valid discussion to have. But in terms of being a pushover, that's a bad thing. Often nice people get taken advantage of. So ther needs to be a clear differentiator between nice pricing/marketing and being firm and leading from the front. A founder needs respect from their team and nice might not make that happen.