I actually signed up for newsletters from some “MLM trainers”

These are people that provide training for people on how to prospect and “help” people (from any MLM). The buzz in the MLM industry right now is that since the economy is down, unemployment is up and people are having a hard time, this is the best time to recruit them into MLM. That would explain why all of a sudden people are seeing MLM ads all over the place. Bad economic times provide happy hunting grounds to kick people who are already down.