Leaning libertarian as I do, keep seeing this topic coming up on libertarian-leaning social media (this thread is a prime example) and so I've been trying to learn about it recently. Based on my research, I think the alcohol analogy is an apt one.
If you can imagine someone who swore off alcohol when he was young and beer was all the world knew how to make. Over the years, while he wasn't drinking, mankind discovered distilling. Eventually the guy decides he wants to try alcohol again, so he goes to the place he used to buy beer, and the guy says "We got this new stuff, rum. Very nice." So, with much hubris, our hero goes home and drinks a 4 or 5 glasses of it.
The active ingredients are the same as they ever were, there is just more of it now in proportion to the inert plant material. In that sense, I imagine it's safer for your lungs than it ever was in terms of the amount of smoke you have to inhale. That of course assumes you know what you are doing with it and not taking way too much because you remember what you smoked 40 years ago.
Different strains are different potency, but they are also a different mixture of active ingredients. THC is the active ingredient which everybody seems to know about, but there are also "cannabinoids". The ratio between the two dictates the kind of high you get. One is mostly mental and can cause paranoia if you have too much without the other, and the other is mostly physical and can cause nausea if you have too much without the other.
Here are two videos I watched recently that are very relevant to the topic:
British documentary about a woman who goes to Amsterdam to learn about this. She makes the same mistake that the author of the article does. She also takes part in an experiment to see how THC affects her vs Cannabinoids.
https://www.youtube.com/watch?v=vJ6bON_8XmcLouis CK telling a similar story hilariously (NSFW language)
http://www.youtube.com/watch?v=wMp7H3hZjsU