This is still only a theory and proves nothing as testing is done on animals and deceased people's brains. It also that this chemical seems to only be present in alcoholics not social drinkers. When there is more literature by reputable establishments, I'll read it.
I've been around all kinds of people in my life and again I'll say that no one has ever claimed that a heroin high is like being drunk.
I am not really concerned with the theory too much but I do know many addicts who attest to the claim that heroin high is very much like being drunk. Not hard to believe if you've ever sat next to one and watched them come in and out of consciousness.
And as to only found in alcoholics, yes. But can you point out the alcoholic before he takes that first drink thus creating the dependence? If yes, then the scientific and health community would love to pay you billions. If not, I'd repeat the assertion that alcohol is a far more effective gathered way drug than pot.
Also, heroin is considered a far "cleaner" drug than alcohol. Alcohol literally destroys every tissue it touches on the way through the human body. Heroin, not so much.
It's all academic though and a little interesting. Not something I'd waste more than an hour looking into unless I were interested in the theory and its science.