The cannabis claim you made sounded interesting to me since I have heard comparable stories.However there are usually quite a bit of unbacked myths circulated so I did some (shallow) research.
These two sites did mention the phenomena of weed use reducing or even eliminating dreams, however they both reported users experiencing extra vivid dreams whenever they stop their (heavy) cannabis use.
This paper could be used as tentative evidence that higher dosage CBD might also repress REM sleep. CBD being the non psychoactive component of cannabis it is usually legal and easy to access.
A literature review did find that THC use has been proven to help with nightmares suffered by those with PTSD. It also mentioned that during withdrawal more vivid dreams were found in one study, and that overall sleep is more disturbed. One study found that this disturbed sleep reduced REM sleep, which should also reduce dreams. However, another found an increase in REM sleep.I hope to have been of at least some service.Feedback welcome