Even your obviously biased source says cannabis CAN cause said effects, it doesn't say it will as you imply.
And from my understanding cannabis doesn't really cause mental problems, it might provoke and strenghten them in already damaged mind/brain.
Just like any other substance, legal or not, cannabis doesn't suit everyone.
I had quite a lot more text here but ended up deleting it since what's the point? the internets is full of accurate knowledge of cannabis, in both it's good and bad qualities, for everyone genuinely interested to find and read.
And this forum does have a search function too. So explaining the most simpliest things to every new Jack, Tom and Harry who happened to find LFS would be just waste of someones time, over and over again.
That's why I usually just ignore such threads, but I do think "You're an idiot" reply every now and then is only a good thing. If even one person starts using his/her own brains thanks to that, it already makes this forum more intelligent place, at least a bit.