Sometimes I go on a reporting spree and do ~30 reports in the Altcoin/Off-topic board. Meanwhile, Welsh has almost 30k reports (which means that he would have received 30k PM in his box).
Sorry, but this isn't a good idea. Hitting 300 good reports isn't that hard.
I can see where it might not work for you or Welsh, but it is really as simple as deleting the message(s) if it's of no use to you. 2 clicks and you can delete a whole page of messages.
For me personally it would have been useful at times, in lieu of anything identifying a post as having been reported. I know this has been suggested as well and would be ideal for any sub 300 reporter.
Either way it was just an idea being tossed out there.