I don't think this is a semantic argument. The comment I replied to was making the argument that alcohol use is widespread because it has no legal competition. This does not appear to be the case to me, thus undermining the argument.
I know that caffeine was a bit of competition for alcohol in the period right after it was introduced (some think that enlightenment was caused by this), but I don't think it's like that anymore.
I'm pro legalization for all drugs, but but I'm not going to dispute the fact that booze, cocaine, and heroin are just like cannabis, caffeine and nicotine because it just isn't true. If you don't acknowledge the reality of people's experience when making your semantic arguments then people are going to ignore you.