Didn’t the patent expire already? So alls good, the genie doesn’t go back into the box.
Interesting to observe that Schnorr's protocol for proving knowledge of discrete log (which for the TLDR people is kind of the "primitive" behind the Schnorr signature) is really actually a tweak on a pre-existing idea from a paper by Chaum, Evertse and van de Graaf in '87.
https://link.springer.com/content/pdf/10.1007/3-540-39118-5_13.pdf
Specifically the construction `s = k + ex` is already present in that work. The main tweak is that Schnorr proposes the variable `e` being a "full" random group element, whereas that paper proposes iterations with `e` being only a bit. It's the same basic thing.
Schnorr actually references it in his original paper on "Efficient Identification and Signatures for Smart Cards", and he also develops the idea more than that, so I'm not accusing of plagiarism or something; just pointing out yet another reason why having a patent on this is so stupid.
(I mean patent aside, it's also of historical interest. Yet another example of Chaum being "the GOAT" as the kids say).
Discussion
Yes it did. But you could argue it did considerable harm over the 15 or so years it was in force.