What do you mean with "halfway back up the tree"? You mean you read a comment C5, and then there are lots of replies to C5: C5-A1, C5-A2, C5-A3, ... but you want to find C5's sibling, C6?
If I want to read C6, so I have to find and collapse C5, C4, C3, etc. in order to see their common parent. And it's hard to tell the difference, especially on mobile, the difference between C5 and C5-A1, or C5 and the parent I'm looking for.
