That’s the challenge of infinite scrolling though, right?
If you’re looking at a specific reply in a topic and share, would you prefer it default to the first post, or the one you’re looking at? With some topics ending up thousands of posts in length it’s typical that the thing you want to share is the thing you’re looking at.
I think we all need a certain amount of reprogramming where this is concerned, previously it wasn’t this way because achieving the same result was quite a lot trickier.