Comment by CGamesPlay

I think it’s just for consistency. A fork and a tree navigation are the same operation conceptually. Now, unlike older Pi, a fork is not a copy of the session, it just has a pointer to the older session. The only losses that I can see are: now /resume shows every conversation rewind; and /tree is harder to implement. Neither of those is provided by Durable, so the gap is left to the implementor.