That's certainly one possible motive. But I don't see why marijuana use can't be motivated for the same usual motivations we see with alcohol use: to promote camaraderie, to relax, to raise the spirits after a difficult day, etc. Each of these motives are lawful motives for using alcohol in moderation, so why would they not be lawful motives for using other intoxicants in moderation?
In the other thread someone mentioned that the MJ of today is engineered to be considerably stronger than the MJ of yesteryear. I have long found this a compelling PRACTICAL argument complicating its moral use, since if the thing CAN'T be used moderately, then it shouldn't be used at all. But with various innovations that allow for micro-dosing and non-smokable delivery methods, it seems this practical argument loses steam. It's still true where it applies, but I'm not sure it applies in many cases.
St Peter says to be sober and watch. But the Psalmist excites us to bless God, 'who maketh wine to cheer the heart of man.' We think of sobriety as a word describing a state completely free of any intoxicants. But really sobriety is the virtue whereby man uses those substances lawfully-- in the right time, right place, right amount, with the right motives, etc.