Pwm is popular now with a subset of vapers who want to control it with a dial. But back in the day it was a big deal to get pwm vapes and considered undesirable. Inconsistent power delivery. Now I see people looking for them. Why would anyone want to go back to inconsistent power delivery?
Don't all regulated mods have PWM? Some just did it better than others, which is pretty much still the case today, unless I'm mistaken. I'm not certain though, so...
That old stuff you're talking about was the original karp out of China, that ran at only 30 hz. I don't think too much is in that range any longer. Even the cheap stuff gives a pretty decent vape.