in recent years it's had some resurgence in popularity, in very small doses (very small relative to doses hedonistic trippers take so they can "see things" that is), because apparently there may be some psychological benefit from it. which may very well be the case.
it's obviously an extremely dangerous drug for any illicit user, mainly because of technical difficulty of ensuring the extremely tiny doses required (for any purpose, clinical or recreational) aren't made accidentally high enough, while making it, to cause serious problems for whoever takes it. which wouldn't be a real big problem for legitimate manufacturers of course, but most black market users can't necessarily rely on the "skillz" of whoever made the stuff they're taking can they. let alone know that what they're taking is even really acid in the first place