Why is that such a surprise to you?
Unless you need hours for a a Rating, License, or some required administrative reason.....why is there a need to log your flight time in a personal logbook?
So long as the proper entries are made in the aircraft logbook/maintenance records to track hours, landings, cycles, etc.....what is the problem?
As Gordy noted....he tracks his flight time and duty hours for Commercial Flying by means of required FAA Part 135 documentation.
That meets the FAA requirements.
Your Authority may have different rules that you. have to comply with....but then that is a different kettle of fish isn't it?