You moved the goalposts. My response was to the claim of a "few" sleepless nights, which is far from the truth for the majority of long term regular users who quit. Instead, you said that there are, "at most, a couple weeks of" mild symptoms. This is simply not representative of the withdrawal scenario for long term heavy usage, both in duration and intensity.
I've seen first hand mentally stable folks who quit smoking marijuana after full time use for a number of decades. The withdrawal symptoms in these folks were far from mild, and lasted more than "at most a couple of weeks". Long term insomnia alone is a serious risk factor, due to their dependence on marijuana to maintain a regular sleep schedule.
While your generalization that marijuana withdrawal is tame may be true in many cases, particularly for light or short term use, it is false for long term daily users.