I moderate a few subreddits over on Reddit and spam purporting to be offers for black market drugs of abuse which use messaging services like Wickr & Telegram have been a problem for years.

Worse, it's shockingly difficult to convince the site admins of Reddit to decisively act on this sort of content, even though it's explicitly against their site-wide policies. I suppose this is probably the case for every site which hosts user submitted content and an upper management focused on easily produced metrics like "number of posts & comments per time unit".