I would say that it's not the plant, but the person. If you use it the correct way for the correct things, it can help. If you use it the wrong way for the wrong things, it can hurt. Basically, like everything. Some people use more than others because everybody has a different body and reaction. Personally, I keep my daily practices sober, since I want them to be strictly training my own will. However, in some workings or divinations, I use it. I find it can also help with dreams, visualization, and deep meditations (besides the regular practice, I wouldn't recommend using it in every single meditation).
Keep in mind that an extra level of discernment must be applied in any working/meditation when one is on cannabis. Usually, one must already discern what is their own mind vs. a spirit. Now, one must discern, "Was it my own mind, a spirit, or was I just high as fuck?" Personally, I haven't gotten "high as fuck" when doing anything magickal. When I use it, I prefer a micro or medium dosage.
I don't find this to be a simple black or white answer. It all depends on you and your practice.
Hope this helps!