I think the industry has grown from the days of the 80s session musicians. At this point youtube subs and social media followers are hard metrics that businesses study and make decisions around. Instead of marketing to broad groups they target smaller, more specific audiences.
I hadn't heard of Rick until this thread, the clip Devin posted above shows the guy knows how to play guitar though. Hes got ~250k subs, not a ton but that's still a quarter of a million potential guitar buyers who probably eat up every word the guy says.
For Rick it's a win/win situation. He gets to spec out a guitar and likely gets a few free copies plus additional cross promotion among Charvel fans who otherwise may have never heard of him.
Charvel gets their name and product in front of his quarter million fans. If only 1% of his audience CONSIDERS buying the sig guitar that's 2,500 people. If only 10% of those considering it follow through it'd translate to ~$700k in sales.
It might be "easier" to market this way than the old school broad approach. Instead of convincing the end user that they should buy your guitar brand, among the sea of competitors that exist now, you use the youtube guys insane influence over their followers to do all the lip service.
It must work, or you wouldn't see these companies throwing signature models at people we've never heard of.
