I think your teacher is telling you all of this, less so that you'll help each other out, and more so that you don't get hyper competitive against each other.
VCE makes people do weird things - some people, upon realising that the VCE is a ranking system, and you get the highest score by being better than everyone else, end up turning it into a "it's me against them" kind of war. After this, they don't help anybody, and end up making enemies and just having a shit time all throughout year 12. It's not a healthy work environment, and I'm pretty sure your teacher just wanted to stop it from happening.
Hell, going out of your way to help people constantly isn't healthy either - they're two extremes that you should aim to not go to. You should just aim to work hard, do your best, but help people if they ask you and need it (assuming you're able, too). Remembering - if you help people when they need it, they'll be more likely to help you when you need it.