People who say too much have little control and will say the wrong thing. Powerful people intimidate by saying less.

This law is about the power of silence. It's why people plead the 5th in the courtroom because the more they say the more they incriminate themselves. Also, most people are not comfortable with silence so it could work to your advantage if you are. 

On the more extreme side, the law is about being intentionally vague to sound more profound. All the profound quotes that people like to recite are pretty vague so there could be truth in this.

I have a really hard time saying less because I tend to think out loud. I had been trying to get a promotion at work. At the same time, a lot of people were leaving during the great resignation. I tried reminding people of my contributions and showing what I could do on projects, but the appeal to logic didn't get me anything concrete. The response was "we're keeping you in mind for opportunities" or "it could be possible in 6 months". Management was sensitive to the fact that a lot of talent was leaving, but I didn't want to have to use that to negotiate. 

One night, I went out to dinner with a couple of my former colleagues, one of which had a reputation for poaching. I casually dropped this dinner into a conversation with my boss the next day. I didn't say I was interested in exploring other options but I also didn't say I wasn't. 

Turns out, it was enough just to let imagination run its course, and within a month, I was able to get a promotion, one that didn't exist previously. By saying less, I didn't have to give people an ultimatum or come up with a counteroffer. The silence did the job for me. A surprising win this week, but I'm sure we'll have more blunders soon.