Yes that is one reason for this section of the forum...to possibly reunite logbooks with the original bike
The second reason is that it also gives members and the Club Registrar a heads up that something may be 'fishy' in the event that a motorcycle, bearing details from an 'Ebay' logbook, comes up for sale or for club inspection in order to obtain an original or age related registration number from DVLA.
Ringing i.e altering the identity of stolen classic vehicles using details from old log books still goes on, with a considerable number then believed to be exported. To do this these days DVLA require the bike to be examined by the official owners club or VMCC to ensure the frame number matches the details on the logbook, before DVLA will issue a current V5C registration document.
I have knowledge of cases where folk have a genuine old bike or buy a barn find that has been stored away for donkey's years, but with no logbook, who then complete a restoration and when they come to apply for an age related number DVLA tell them that their frame number is already allocated to another machine. That 'other' machine then has to be located and examined by the Police and usually turns out to be a 'ringer'. However, if the 'other' bike has been exported it cannot easily be examined and the owner of the genuine bike then has a real problem getting it registered.
So..uncancelled logbooks can be of significant value to the low life thieves.