There are a lot of reasons to not feed wild monkeys. They become too familiar with humans and start attacking hikers and stealing food directly from apartments and grocery stores (all of these things have already happened in this area). They also become too dependent on humans. When there are less human traffic at the park like the day we visited, the monkeys starve. But people keep feeding the monkeys because watching the monkeys eat is entertaining and they think the entire interaction is cute.
Monkeys do not share food with monkeys from other groups. In the video, you can see an older monkey steal an orange from a baby monkey that was by itself.