Why arent Muslims allowed to be friends with the other ,if it has nothing todo with being in a relationship?

I've heard it is forbidden for two non-Mahrams to even be friends with each other. And only talk if there is something that is extremely extremely urgent to talk about, and even then avoid it in all cases. I find this extremely harsh. Men will always come in contact with women, whether its an educational or work environment. If you want Muslims to be completely cut-off from the opposite (non-Mahrams) for the rest of their lives, that is way too extreme. Women should be allowed to be friends with people other than their same , and to suggest otherwise is ludicrous. We do not live in the Stone Ages anymore. We are not all ually starved just by talking to a woman. I'm not even talking about relationships or pre-marital here, platonic friendships.