There's lots of evidence that THC on its own can cause serious mental health problems (other than addiction). So no, in this case we should not "ignore the substance"
Yes... To people who already have or are susceptible to mental health issues. Alcohol or any other intoxicants, including prescription drugs could be just as dangerous for these types of people.
Less that THC causes mental health problems, and more that existing mental health problems are exacerbated by THC.
>There's lots of evidence that THC on its own can cause serious mental health problems