Well, I think you're right about people underestimating the support of snowboard boots and bindings. I snowboard a little, and quite stiff gear is available.
But also, all the people saying you will get hurt are right. This is what you need to be careful of: if you fall backwards and twist to one side, the front tip of your outside ski will prevent your outside foot from twisting with you. So, that leg will end up folding underneath you with your toes pointed outward at a big angle (kinda hard to describe). This will tear your anterior cruciate ligament (ACL) and your medial meniscus in your knee. This is a very common football injury (cleats stuck in the ground stop the foot from turning also) and used to be a serious skiing injury before Marker invented the releasing binding (although it is still pretty common). So, be careful, and be aware this injury has an up to 6 month recovery time and can require surgery.