Only the time from take-off to landing went in the logbook. Taxi time was never recorded.
Yes, the good old days! It was the same here before JAR/EU/EASA-FCL. Time in the logbook was time spent in the air. Nothing else. I value my pre-JAR logbook entries much more than those after, because I know that all this was real flying time. From then on, I can't even tell what percentage of the time was spent on the ground. Add to that co-pilots (or first officers if you prefer - I don't) who are eager to unfreeze their ATPLs in the shortest possible time and therefore put ridiculous taxi times on the log! (I must be the most hated captain in our small operation because I don't allow them to log more than ten minutes of taxi-time - unless it was reallllly long like in Frankfurt or Barcelona.)
The only reason to log taxi time alone that comes to mind is to generate some written record of the fact that you have been on duty that day, either as pilot or instructor. Otherwise the bean-counters may count that as an off-day. But for private flying certainly not.