Date Displayed on Check in Page

The date displayed appears to have no functionality. I assumed the date selected here would be the date the check in posts would use. So for example say I would like to enter all medications for yesterday because I forgot to enter them. It seems the point of the date field would be for this reason. However that is not the case. If I change the date on the check in page to yesterday all medication check-ins I enter are still posted to current date.
I realize I can change the date and time while entering the medication, however it would be nice if the date selected on the check in page was date used by new entry otherwise Im not sure I would see any point for this date to be on this page and for it to be able to be changed to previous dates.

Hello, we are rearchitecting this for the next version (v4.0). However, the date currently is used for Diary entries, Measurements, and other trackers that only have TIME that can be selected.

The complexity arises from trackers like Sleep that span over 2 dates, and the same can be the case for some activities. Also, we need to determine what happens if cards within Trackers are set to a certain date + time and then the date is changed, do we override them or only apply it to new cards being created?

What are your thoughts?