since 2016, new date fields options are added.
these fields do not work on calculated fields functions that include full datetime field (aka date only field is not supported
in function such: DIFFINMONTHS (, NOW())
Fundamental calculation that is needed in most CRM implementations is current age based on birthday field (Date Only) for contacts. Currently cannot do this without adding a secondary date/time field for birthday, which then allows the usage of NOW() in the age calculated field.
This is a pretty glaring gap in the calculated field capabilities that arguably should be addressed quickly.