Is this really surprising? Any time I had used cannabis I felt like my IQ dropped 20-30 points and I would lose hours of my day where it was difficult for me to learn. It made doing household chores not terrible, but brought out a lot of panic inducing moments and erratic behavior. I was thinking about a 100k other things while doing one thing. Later on I realized I wasn't even doing that one thing so well. Anything…
I think the greatest problem with marijuana discourse is that it ignores the large variability in effects. For me, and apparently for you and for many others, the description above is exact (which I found entire extremely enjoyable, of course). For others it’s very different, allowing them to function completely normally.