You are correct, there are many other reasons for saving dates and times in a database apart from recording "events", and for those it does make sense to use "relative" descriptions of time or date. I'd argue though, that if your data collection of events is imperfect, like if you have no idea which system an event came from or whether you can trust the syntax of the timestamps, those are primary problems that should be fixed and not "worked around" by changing how your timestamps are saved.

For example, if you don't know where a data point originated, that's already a pretty big issue regardless of whether the time is correct or not. If you have financial data with ambiguous timestamps, this is not only a problem but potentially a compliance problem, since banks are heavily regulated. I think it's unlikely that it's acceptable for a bank to be unable to answer the question "when did this event take place", so the fundamental issue should be fixed, not tolerated.