I'm sure a Hobbs is more accurate than many wind up wrist watches!
At the club I fly at in the UK we log time from take-off to landing, for billing purposes, then add 0.1 (or 6 minutes for the non decimal loggers) either side for taxy, for log book purposes. Hardly accurate is it? So as far as I'm concerned people can log the time how they see fit (as long as its not grossly in error), as inaccuracies will creep in using which ever method. All this arguement does is add to the already growing mound of beauracy which is boggin down GA in the UK to such an extent that people no longer want to fly there !