1) Dates are often stored as strings, so parsing them correctly is a necessary component of storing them. Also, those dates need not be simple app state. They could come from an API provided by your doctor/pharmacy

2) Many people (especially the elderly) take enough medications on different schedules that managing them all would be a significant cognitive load for anyone

It’s just an illustrative example, though. My point is getting dates right (including parsing their string representations) often matters quite a bit. If you disagree, let’s argue about that rather than quibble about the minutiae of the example