Actually registration would do nothing to find the owners of existing derelicts. If anything the publicity could be self defeating: got a boat for scrap? Pay someone £1000 to deal with it, or take it to the Fal where they do it for you for free...!
At least they recognise that compulsory registration would be a nightmare to get off the ground.
Take a walk through most boat parks & you will see derelict end of life boats, in our club i estimate 30 - 40% are at that stage. The covid pandemic & following cost of living crisis has hit many people hard & Many owners are now old & unable to accept that their boat that cost them 12k twenty years back is now worth a fraction of that if anything.
If people default on subs & are chucked out the last thing on most peoples minds is getting rid of their old boat, out of sight out of mind kind of thing.
But it isnt on or feasible for members to have to become boat breakers & clear up other peoples crap!