Yes, mold IS very dangerous. Especially the types of the fungus that produce and release TOXINS in the air. Black mold, for example.
Health problems related to this mold have been documented in humans and animals since the 1930s. More recently, Stachybotrys Chartarum has been linked with so-called sick building syndrome. Stachybotrys Chartarum is a mycotoxin producer that can cause animal and human mycotoxicosis*. In one particular 1993-1994 case, Black Mold was implicated in the fatal lung hemmorhages of several infants in Cleveland, Ohio. Stachybotrys Chartarum will grow readily on the unseen paper backing of drywall, ceiling tile, paper moisture barriers, wallpaper, and other paper or wood products, especially in bath and shower areas where constant moisture is present. Symptoms of Black Mold exposure can include cold and flu symptoms, chronic fatigue syndrome (CFS), memory loss, achiness, diarrhea, headaches, sore throats, dermatitis, hair loss, and even cancer. Animal tests have indicated the mold attacks the lungs, brain, thymus, spleen, heart, lymph nodes, kindeys and liver.
I got that little snippet from the post in this thread. You don't have to be allergic to mold to breathe in the toxins it can release. So again, yes - mold is very dangerous. Whoever told you otherwise is dead wrong. A 5 minute internet search can give you all of the information you need.
*mycotoxicosis is a disease caused by any fungal toxins (called mycotoxins)