Database Design

Recently I see an increase in questions in various forums (including Stackoverflow) where people are using (big) integer values instead of proper timestamp values to represent timestamps values (less so for DATE values though).

All modern databases systems provide highly efficient data types to store real timestamp values, but I often get questions asking what the actual downside of using a “UNIX epoch” instead of a proper timestamp is.

I have been wondering for a while, why there are so many databases where all well known best practises for good data modelling are thrown overboard and the wrong data types are used.