If you want to improve your relationships though, make rule zero "minimize the extent to which you require other people in the world to change."
I'd say make sure that if you do push people to change, it is for their benefit rather than yours.
I find the "uncover your feelings" the most questionable point of the whole framework. Instantly reminds me of Stephen Fry's
— I am rather offended by that
– So fucking what?
If someone is told the words "I feel a lot of anxiety about our financial stability" it's completely possible for them to understand the "true meaning" as "You're a useless slob who can't hold a proper job and I hate you"
But this doesn't mean that words don't matter. We don't control the meaning we convey, but we do influence it. Choice of words and phrasing is a very powerful tool for that. There are other tools as well, of course. But getting the words right is the low hanging fruit for most people.
I actually think this is profoundly awful advice, that gets progressively worse the more intimate the relationship, as a fundamental function of human relationships is accountability.
That is the central point of NVC though. It isn't a mind trick to make people change, it is a framework for someone to communicate how they see the world without requiring anyone else to change.
Your rule 0 combines with NVC to lets conversations drift into meaningful topics while allowing other people to change only if they want to.
Your rule 0 without NVC basically means you need to rediscover NVC yourself or you have to limit your conversation only to the superficial. Which is workable but sub-optimal.