It's a well-accepted (but not always followed) unwritten UI design rule that if you show a relative timestamp like "two weeks ago", it should show the exact timestamp on hover, plus an affordance for non-mouse usage (mobile, people that use keyboard navigation, etc) such as being able to tap/click it.
I like them as long as they let you tap it to get the actual timestamp. If they're being used to obfuscate the actual time, it's just annoying
It's a well-accepted (but not always followed) unwritten UI design rule that if you show a relative timestamp like "two weeks ago", it should show the exact timestamp on hover, plus an affordance for non-mouse usage (mobile, people that use keyboard navigation, etc) such as being able to tap/click it.