RC vendors were generally selling NBOMe's as NBOMe's on the net. However, because they were so cheap, plenty of dealers were re-selling on the street as "LSD" or "mescaline" (even though an active dose of mescaline cannot fit on a blotter). Let's face it, barely anyone even knows what 2C-B is, and that is probably one of the more popular psychedelics - far fewer have ever heard of things like DOC or 25I-NBOMe (especially back in the day, where it was effectively unknown outside of a small circle of neuroscientists trying to label serotonin receptors), and they're consequently much harder to sell.
The problem with LSD is that it's not like meth, where any idiot can set up a "lab" in their tool shed with a few relatively basic ingredients. Making LSD has significantly higher barriers to entry, both in terms of quality of the equipment / skill of the chemist, and the availability of a very difficult-to-source precursor (ergotamine or lysergic acid). Once you have all those, however, a single lab can theoretically supply an entire continent - after all, just 1 kilo of LSD would be enough to make more than 10 million hits. This means that when a major lab gets busted, supply drops dramatically.
NBOMe's, on the other hand, are considerably easier to synthesize, and used to be completely unscheduled in either China or the West, so it was easy for RC vendors to find random Chinese labs willing to churn them out on the cheap. So when ~10 years ago, there was a massive drought of affordable LSD, dealers were only too happy to step in by selling NBOMe's as LSD.
Nowadays, most of the NBOMe's are banned even in China, and LSD is once again easily available, so the chance of stumbling across fake acid is considerably lower than it used to be.