Whenever a user sees a date or time, he/she start doing comparisons between current time and given time. So it takes some more brain resources to do time difference calculations. Facebook knows about this lazy human behavior, that’s why it always shows date time in the following format
less than a minute ago
17 minutes ago
1 Year ago
Instead of
30 May 2018 15:35:47
30 May 2018 15:18:33
23 May 2017 09:28:23