Killing quest trees/rocks etc not on your claim should leave a brutality of nature scent, that will be trackable for 10 days. Doesn't require theft, but will warn you before you attempt it.
Doesn't stop you from logging out, but people will know which bastard diddly dun did it! Maybe people just use alts and grief the quest givers with no consequence or care, but I still want closure for this injustice.