Drug addicts to other drugs cannot smoke it without off/odd effects and even serious anxiety because it Causes vulnerable to the "truth" of how Your life feels.
cannabis serves the purpose of making you feel however you would feel if you stop lying, and that could be good or bad.
For people who get anxiety or uncomfotable on marijuana alone or mixed with drugs: notice how it's so easy to keep fighting everything in your mind after marijuana with more stress, but it feels even more relieving to imagine surrender and relaxation but anxious pot smokers will nonstop resist and overdrive their minds from the light Pot reveals.
It's like a drug that's only euphoric if your "doing it right" in your head/mindset already otherwise it fucks you.
That's why it's bogus to so many because they wanna correct shitty feelings and pot doesn't do crap for them. It's the drug you still have to be trying in your life to get relief from.