It’s not even anecdotal. The relative risk for developing schizophrenia for cannabis smokers vs non cannabis smokers is 2.3. This means that you are 2.3 times more likely to develop schizophrenia if you smoke cannabis.
Reporting relative odds or risks without a baseline is very misleading. The absolute risk in either case is still very low. People aren't downplaying risks.. they are setting them in a proper context (where other legal recreational drugs cause substantially more harm).
Schizophrenia is an imbalance in the polyphony of minds occupying our heads. Our minds and bodies take training to pilot properly. If we want to have agency, we need to be methodical and purposeful in what we do and don't vastly surpass our current limits. You can't go squat 400 lbs w/o training. The same goes for mind altering substances.
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988731/
With that said, I think it should be legal. I just think people shouldn’t downplay the risks.