The problem is non-aggression pledges can still be used in dishonest ways. For example, a lot of big tech companies file thousands of flimsy patents for things that should never be patentable. They collect these so that if they are ever in a lawsuit, they can fire back using these dishonest patents. The problem is this means the organization with more power and be more abusive. If someone like Amazon or Apple copies your great patented idea, you’ll not only face an uphill battle in the courts for years - by which time your business may be dead - but they’ll also have ways to make life harder for you using the patents they’ve collected.
The real fix is still reforming the patent system entirely.