The only place I see post numbers is on the scroll bar. However, it is a bit tricky to determine which post it belongs to. Add to that that the scroll bar is no longer visible once I am on the last couple of posts because it ends before the end of a thread and ads show up below it. So for me to see that the last post in this thread is #501, I have to scroll back up to post 499/501. That is annoying. (tablet, desktop view… mobile is a bit different)
I am getting used to the “conversation groupings” of replies showing below a post and the ability to open a replied to post. Although the jumping around gets confusing, especially if you step away. But I don’t like not having a post number easily displayed on each post.