I have seen a lot of deer in bonfire the past two months, they're normally on the side opposite the hill, mingling with all the horses. Though when ever I head over in that direction, I hardly ever see power playing or illiterate deer, there are a few of course, but mostly the only problem they seem to have is that they haven't researched deer at all so they don't know their behavior. Most of them are quite polite with the predators who want to hunt them, and I have only seen a few incidents when they try to chase anyone away from their role play.. Though I do have to admit, a deer walking up to a dragon and trying to chase it off by growling at it is a little weird, but I have also seen horses and sea lions do the same, so what ever.
Personally I think if the people are all having fun together playing deer (or anything else), then there is no problem with the amount, as long as they keep things civil and don't try to force people away with insults and bad attitude.