While auto scroll back in history is useful, there is some room to make going back in history very far more efficient / user friendly:
Please implement a mechanism to go back via some mechanism by weeks, months and years.
A calendar might be too bulky, but some kind of a slider or button / tab arrangement might make this fairly efficient. It might be possible to put some kind of draw / slider at the top that you can pull down and navigate it more like Time Machine in macOS.
This is especially a problem for those of us who have moved to MatterMost from other messaging systems (HipChat, Slack) and other services where we have years of history and some projects and notes require such navigation.