I think the meaning of "folk" is clear enough. It's people who are fuzzy about the meaning who tend to confuse the issue.

Oftentimes there is a selfish motivation, for example, the person who writes his or her own songs and wants to "legitimize" their songs by claiming they are "folk."

Like the example I give above: the guy who makes a chair in his workshop, then puts a high price on it and tries to peddle it as an "antique." Basically, a scam, claiming a prestige it doesn't deserve.

Don Firth