IMO it all comes down to bounty managers and their way of preferred collecting report, although a lot of them actually states the work of previous weeks shouldn't be quoted but, some participants are just so dumb or ignorant to the rules.
I think the best solution to these sort of spam as well as unnecessary bumping of the bounty thread is to restrict or allow each participant with just one post on the bounty thread, they should write their authentication posts and edit it weekly to add task reports.