The threat of potential evil-doers operating a boiler room type operation primarily. The basic problem with regulation of the form "this type of solicitation is

The threat of potential evil-doers operating a boiler room type operation primarily. The basic problem with regulation of the form "this type of solicitation is ok, but not this" is that the government tends to be behind the curve. Logically this makes sense; the government can only ban certain types of abuse after they have been deemed as such and after they have already happened. If your goal is to protect the 401k of a soccer mom who isn't good with the googles the easiest way to do that is just ban private placement solicitations entirely.