Also there's a very important difference: Soma is described as non-addictive, no hangover. It's a way to control society but keeping it productive at the same time. Any drug that causes "epidemics" that result in death or defeating from work would be useless. You can argue that it's enough that most people keep working though, even if a fraction gets trashed.

Edit: if anything, social media or other addictive distractions are more like soma.