The majority of people have felt the effects of alcohol, and most of those have been properly drunk at some point - so they know what it's like to take something which profoundly and very noticeably affects their consciousness.
If a drinker says "I just don't understand the appeal in taking drugs", the implication is that there's some property common to illegal drugs that alcohol doesn't share. There's not; the only characteristic common to all illegal drugs is that they alter consciousness, and they absolutely share that characteristic with legal substances like alcohol, caffeine, etc.
The argument is not meant to equate LSD with caffeine; just to demonstrate that taking illegal drugs is not some categorically different thing to taking legal drugs. Once you break down that distinction, what's left to argue about is the pros and cons of each individual substance, which is IMO a Good Thing.
I just think that saying "I've never done drugs" while at the same time admitting drinking alcohol is kinda silly.
Some of the 'drugs' the guy talks about in the section about his daughter are caffeinated drinks and alcohol.
I also happen to think that these false distinctions (marijuana is a drug, alcohol isn't, oxycodone is different because it's a doctor-drug) do the debate a lot of harm.
I'm not saying you're wrong, mind.
Thanks to decades of propaganda...
I would be personally be much more inclined to believing the scientists whose entire career is the study of these illegal substances rather than the politicians who have to continue pushing the old ideals of "this is the line and we do not move the line because that would be an immoral attack on the fabric of society". Do you know why cannabis is known as marijuana? The reason is the old guard felt that cannabis was not foreign enough and changed it to something a wee bit more scary.
If you can put out a well reasoned argument against legalization then fine. If you will fall back to the standard catch all of 'its illegal!' then we have nothing discuss for you cannot present a reasonable argument.
edit: spelling error