A post share link and a normal post link have these orthogonal advantages:
- Share link:
- has poster ID => get a sharing badge/track its usage
- short => useful in a severely space-constrained media
- Normal link:
This results in a dichotomy for users, as they have to decide each time which of the properties are more important for them at the moment.
(I personally almost always choose the normal one: link rot is a serious problem on the Web so I don't contribute to it; I don't use space-constrained media like Twitter; links that lead God-knows-where and page reloads on jumping to another post of the same Q&A are damn annoying and I'm not someone who would violate the Golden Rule.)
Now, all of the listed link properties are important. And they aren't mutually exclusive (except the shortness). So, why do I have to choose only half of the benefits and lose the other half each time if it's technically possible to get all at once?
Tech-wise, it doesn't look like rocket science to concoct something unambiguous. From the top of my head (just an example, feel free to suggest others):
I would even propose to make this the default link sharing format (this is a separate concern, however, so vote on this separately, please) since space constraints are nowadays mostly a non-issue. The short form is going to stay, too, of course, because for a minority of use cases like the aforementioned Twitter, they still are.