It is. If it ever crosses (generic-you) your mind to do that, don't. The revenge is very unlikely to be worth the very significant legal risk you are incurring. Stick to tradition and bad-mouth them with friends at a bar.

or write an angry blog post

or start a rival company and put them out of business, by slowly taking away all their main clients and then winning a case in court overturning the noncompete agreement using legal precedents in your state.

That escalated quickly, no? :)

I'm pretty sure that's a criminal offense in most countries in the world. You're destroying company property, at least.

It's the best way to destroy your career and really become unemployable, even if you don't go to jail.