Ummm...hate to break the news to you, but those sites are just wrong, there are no withdrawal symptoms. And the isolation theory...what a joke. Those sites are scaremongering. Everyone I know that smokes lead productive lives, some are professionals, you would never even know they smoke.
Except for the secret handshake. ;-)
MARIJUANA
The marijuana smoked in the United States consists of the flower and dried top level of the flower and dried top leaves of the plant cannabis sativa. Unlike alcohol, relatively simple chemical, marijuana contains over 400 chemicals, 60 of which are unique to the marijuana plant. Marijuana, when lit, causes an additional 1,600 chemicals to be formed. As the pot smoker inhales, these chemicals invade every cell of the user's body. The ingredient that creates the "high" is Delta-9-THC, commonly referred to as THC. Like alcohol, marijuana is a central nervous system depressant. Pot, like most other drugs, wears down the motivation of users. It erodes the will to perform. Ambition is lost. Success and achievement no longer matter to the chronic marijuana user. In addition to the unknown short- and long -term dangers of so many chemicals entering the user's body, THC has a particular characteristic that increases its harmfulness. THS is soluble in fat; THC is not soluble in water. Since our body gets rid of its waste through a water system using urine, feces, sweat and blood, THC cannot escape. It stays trapped in the body. In addition, THX finds it's resting place in fatty parts of the body. The most sensitive and critical are: the brain, the lungs, the liver and the reproductive system.
There are credible reports that people do experience some withdrawl symptoms following chronic, long term heavy usage. There are also clinical reports of people suffering hallucinations from drinking copious amounts of water over a period of hours. It is a "fact" that marijuana is addictive and causese withdrawl symptoms, just as it is a "fact" that water is a hallucinogen.
If nothing else, these threads provide material for consideration of the difference between "facts" and "truth".