We can have a lot of cards stuck in one stage of the pipeline and they are all in "follow up conversations".
"Days from last update" is not helpful because we never need to update the opportunity card info, and conversation flow is not considered "update".
With this field, we are able to display and track when was the last time we send a message to the contact and know who has been sitting on the pipeline longest and we can follow up accordingly.
In conversation we can filter by last message direction whether inbound or outbound, this should be carried over the same in opportunity.
Imagine having to display "Days from last inbound" and "Days from last outbound" on the opportunity card this can help us sort and know who we already last follow up and we can either wait or follow up again.
"Days from last stage changed" is not very helpful when sometimes contacts do need to stay in that stage for a longer time, like we are negotiating or following up with the leads, but this conversation activity is not reflected on the pipeline. It's not very feasible to break every follow-up a stage by itself.