Leaving links in battles after leaving feedback will always be allowed... at least it'd be public record.

As for disallowing PM asking for votes... had to do with people abusing it and all the problems that go along with it. People send a PM to someone and when they get voted against, they complain. Then we have those people who PM saying something like "I'm being cheated.. vote on this battle honestly" <-- Yes, I did read that and that is called swaying.