Dps low, healer goes oom, healer takes blame.
Tank doesnt have enough mitigation healer goes oom, healer takes blame.
Dps stands in fire, healer goes oom, healer takes blame
Tank overpulls, it looks fine till healer goes oom, healer takes blame
OP, don't let this person scare you. It's true that the healing model is changing, and things are going to be harder (for everyone), but the "new" healing model is actually a step back to how things were before wotlk. If you played in BC, then you probably remember when heroics actually required people to know what they're doing.
If your dps is too low, your group should fail.
If your tank's mitigation is too low, your group should fail.
If the dps stands in fire, your group should fail.
If the tank overpulls, your group should fail.
Everyone needs to do their job, and do it well, in order for your group to succeed. The only alternative would be to have easy dungeons, where players are not penalized for making bad decisions. If other people blame the healer for their own failures, they're going to have to learn quickly or else they're not going to get very far in cataclysm.