Let me try explaining again. If this link gets out into the world…
https://meta.discourse.org/t/nice-share-for-posts-without-links/145665/3?u=codinghorror
See how it says u=codinghorror on the end? That’s the important part for the purposes of this discussion.
Anyone clicking on that gives my account “credit” for the share. If enough unique IP addresses visit the page from that URL, I will get the share badge because enough people (could be you who shared the link, could be me… could be anyone) clicked on that particular link with my username in it.