The latter can be defeated in court if there is evidence of such fraudulent appropriation, but then again, if the discovery of that appropriation is not dealt with within 3 years, no legal remedy is possible.
So, the two work together like this:
I make a work, and have it up on the interwebs. Somebody steals it, starts selling it, and makes a business out of selling it. I do not know about it, and thus do not shut it down in a timely manner (within 3 years). As a consequence, when I DO find out about it, I cannot seek legal remedy, due to Laches, and Estoppel. He has essentially stolen my right to control distribution and derivative works of my work, and due to my negligence, I am unable to fight it.
In regard to something patentable, it is first to file who gets the protection. So while I might be able to get his patent invalided by showing prior art, he is still the one who gets awarded the patent-- not me.
That there is a risk of losing this protection/control over intellectual property, companies with a vested interest in that IP actively and viciously enforce their rights. That is why a market that allows resale of mods directly without paying the Bethesda Tax (tm), would be immediately and aggressively torpedoed by Bethesda's attack lawyers, lest the site exist for more than 3 years time, and become immune, making Bethesda unable to stop appropriation.
For a specific use situation where it would come up in the TES mod community specifically-- Let's say I am the creator of SkyUI, or some similar highly utilized tech mod. Other people incorporate my work, and produce derivative works from my work, and I do NOT crack down on them for 3 years after they start using my work without seeking license from me. This removes my power to legally compel them to stop using my work should they decide to then use their protected user status to sublicense their immunity with their own licenses to my work. EG-- While I might switch to a paid model, they can fork my mod as it was when it was incorporated 3 years prior, and continue development of it outside of my control, and there is not a god damned thing I can do about it.
Now, extend that to art assets used all over the place, code segments used in scripts, etc.
Do you see the clusterfuck yet?