Sorry, missed this one. Pretty sure that Rigid didn't develop the first circular saw and Craftsman didn't develop the original combination wrench. If you really want to complain about parts interchangeability and straight out duplication, lets talk about the Taurus 92 series of pistols which were built on the production equipment that Beretta sold them after the patents expired.
You have to remember that a patent and a copywrite are 2 different things. You can't publish a document that I have a copywrite on and call it your own. A patent, on the other hand, has an expiration date. If you have the patent, and choose not to renew it, other companies can take advantage of it without paying you to do so. This is not a new concept, and it certainly didn't start with the Chinese. The Chinese are good at it because they make so many parts for so many companies. As such, when a patent expires, they know about it and are first in line to take advantage of it if they want (I'm pretending here that they aren't actively violating international patent laws where it suits them).
Realistically, the fact that I can buy replacement parts from my Stihl dealership is a huge bonus in multiple ways. Its makes things easier for me AND it puts some of that money I saved into my local economy.
As far as Chinese plants only making good parts for other companies, that's a misguided statement at best. One thing that all asian companies have done a good job at for the past 70 years is respond to their customer's demands. Japanese cars used to be considered junk and now they outlast the big 3 by a wide margin. I routinely get over 300K out of a Honda or Toyota. Honda small engines are literally legendary, and Japan made almost every diesel engine for <40hp tractors for several decades. Korean imports started off the same way, cheap junk. Now their exports are typically superior to our domestic products.
As others have alluded to, this conversation really isn't about Chinese chainsaws. It's about why America struggles to compete on the global manufacturing stage. Why do we allow people to make decisions just because they have a degree when the only thing that degree taught them how to do was generate a timeline and a PowerPoint presentation? I've personally witnessed this process bankrupt and destroy at least 5 major (multi-billion dollar) corporations. I would absolutely love to always buy American so long as it ment that I was buying products that were truly made in America from companies that were efficiently making the best products. At this time, buying American just means that I'm financially encouraging companies to continue to do what they are doing. In most cases, I think that's bad for our country.