Not sure what kind of car you like or drive but if that applies to all corporations we would all be driving a Benz since he invented the gas powered combustion engine.Minelab is a for-profit business and, in fact, publicly traded so its priority is its shareholders. That's true of most companies. If ML can use the patent system to restrict competition and make more money then that's what they should be expected to do. And if they can create a de facto monopoly then, again, expect that, too. Keep in mind that patents aren't forever, they expire after 20 years. But drug companies have been gaming the patent system by making a minor tweak to an expiring patent and getting another 20 years out of it.
Other detector companies can also play this game if they choose. Problem is, most of them are badly lagging ML in R&D and don't have much to patent. Garrett has patents on their ProPointer design that could be used to shut down all the clones but they don't even enforce the patents. I filed several patents at White's and 1 at FTP, probably nothing will ever be done with them. That's the other thing about patents: they only give you the right to sue someone. Doing so has a starting cost of about $100,000 so you better have deep pockets or a guaranteed winning case.
Minelab is playing the corporate game like a real corporation, not a mom&pop garage operation. No, the detecting community doesn't benefit from this at all, but that's how the rules of the game are set up.
Or I suppose we would all be stuck driving a Ford, using only one brand of firearm, watching the same television set, swinging the same set of golf clubs, you get my drift.
Competition and choice is a good thing.