Because most people aren’t so offended by it that they choose to avoid people with such opinions altogether (I’m not talking about not wanting to be friends, but rather, being offended). Such sensitivity is atypical by definition. It’s not intended to be an insult, merely an observation.
Besides, how does it possibly help you (or anyone else) to get emotionally wounded by some random stranger on the Internet's insensitive comments? Most people older than their 20s have figured this out already and are living more productive lives.
