I think that would have its own issues, such as creating a significant burden on both the person filing (who the system is designed to protect) as well as the patent office having to verify the implementation. I think it would be very complex.
Really, patents should just expire after 5 years by default, possibly with exceptional grants for 10 years. I think 5-10 years is plenty of time to establish yourself in a market, and if at that point your competitors start competing, well, you had your grace period.
No, because one of the traditional use-cases why patents were made is so that an inventor of a novel solution can get investment to get that invention actually implemented without risking that the investors will just steal the invention; or that the inventor can contract a manufacturing company to make the prototype without risking that they will just include the invention in their own products.
So being able to secure a patent before its first implementation is made is pretty much a non-negotiable requirement.
Patents are often not directly exploited by the holder; instead, the holder sits and waits decfor someone else to build a working tool, then sues.
So, yes, folks should be able to secure a parent before they're able to build and sell a working product, _but_ it should be a requirement that they build and sell within a shorter time-frame than the length of the patent, e.g. the patent is for X years and I have to build and sell within 0.2*X years or the patent is rejected.
It seems to make sense, but is problematic in practice - for example, for pharmaceuticals it might take half of the total patent time until you are able to sell a product based on the patent, as getting FDA approval could take something like 8 years if they ask for more trials.
Also, patents make sense also for things that are not for sale to general public - for example, an invention to improve some machines that you use in your factory, but aren't selling to other factories i.e. your competitors; consumer products are the thing that is visible, but B2B products matter even more.
It could also be fixed by making the penalty for filing an invalid patent prohibitively high. If someone proves prior art, you have to pay them "a mountain of cash". That way, there's A) a real risk in making your patent any broader than it needs to be and B) an incentive for law firms specialize in killing patents for the reward payout.
That's going to make it way easier for large companies who can afford a team of lawyers to hunt through potential infringements (and defend them). The cost of filing a patent is already really high (1000s, 10s of thosands) even without that.
