I think it would have been neat if someone created a browser-extension that let users contribute such data, but I guess preventing abuse could prove to be an im

I think it would have been neat if someone created a browser-extension that let users contribute such data, but I guess preventing abuse could prove to be an impossible task, since there is no way that I can think of for a third-party to check whether the user really performed an action without having to perform those actions for the user, in which case we would have to trust our login-details to that third-party.