This is perhaps the best way to actually protect yourself in some business situations where enforcing the patent and getting it in the first place is going to require too much effort for the given use case. You can just post a sealed copy of the invention to your solicitor, then crack on with making the product. If someone beats you to market and wants to sue you for copying their patent then you should be covered nicely, you have hard evidence you have not stolen 'their' idea.
You also don't have to publish for the world to see what your key invention is. If it is a manufacturing technique that is required to make an existing product more affordably then you can keep your invention secret that way.
Snopes describes the "poor man's copyright" as not useful in the US, "may" be some use in Britain: https://www.snopes.com/fact-check/poor-mans-copyright/
But is has. It's the changes in the patent system in the past decade that is forcing this patent troll to shut down. To wit:
* The US changed from first-to-invent to first-to-file. This reduces opportunities for patent trolls to patent obvious stuff that other people invented.
* Bilski and Alice have very firmly shut down the motherlode of crap arising from the State Street decision. Business method patents, and "do X on a computer" are quite invalid.
* Inter partes review makes it easier to challenge patents, and SCOTUS last year upheld it as constitutional.
* Venue shopping to get that one court that will always rule in favor of patents got a lot harder, as the TC Heartland case says you can only define the residence of the corporation as its place of incorporation.
* Prior use defense: if you used a method before it was patent, you don't have to pay to license the patent.
I think there are some other reforms that could be made (the big one is moving from one fixed term for all patent categories to varying it by industry), but life has gotten much harder for patent trolls.