I like it :D There will be people who can find some disadvantages for sure, but I don't see them so far and I would definitely donate some of my VP if someone would build a tool like this.
Flagging is probably the one thing we really need to do 'centralized' so we can combine our powers and have greater impact. MarkyMark has made a global blacklist which is great, here we combine data/knowledge, combine it with a 'global flag tool' and we can maybe create a serious dent in the efforts of some spammers.