Marijuana absolutely can and does cause far more significant withdrawal than just a few sleepless nights. Under certain circumstances, the withdrawal can persist for much, much longer.

It's irresponsible to assume that marijuana is harmless and non-addictive or only mildly addictive, and too easy to justify as being benign, when juxtaposed wth the withdrawal process of harder drugs.

Not really, marijuana withdrawals are fairly tame and many people don't even experiences those. At most, a couple of weeks of irritability, appetite issues, and problems sleeping.

The psychological "withdrawal" can be much worse, but there is a whole range of regular things that can lead to those addictions. And it is often abused to hide other mental health issues, which can flare up while quitting.

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.

I moved the goalposts to "what our scientific research has found," not to some anecdotal evidence of a particularly bad psychological withdrawal someone you know had. That wasn't the drug's fault, and your friend could have done many innocuous tasks before sleep and had the same problems quitting.