These are soft drugs and should be legal simply for drying out the black market. And have them available in a controlled manner.
Many things in social circumstance seem to depend on booze: >lets get a drink >lets hang out at _x_ house, bring a six pack >lets get drunk and watch __
The same doesn't work for marijuana at least in lots of verbal contexts (being over heard by your superiors.).
Now you might even argue that hearsay is not 'data', but in fact it is: for instance, there is quite a bit of NLP literature on trying to identify unreported side effects of medications from 'informal' channels like social media. Even if it's a second or third or fourth report, it is a report nonetheless, and should be taken seriously.
So let's not be gratuitiously negative [1] about people's negative reports about marihuana, no matter how biased you might think they might be. This is one of the most dramatic public health changes since the Prohibition we're talking about, so what is at stake is the health of millions of people for possibly many generations --so even very small effects otherwise considered too rare to matter might have an outsize impact on large segments of society.