I would actually tend to agree with the requirement that you don't need at least one of those people to progress musically. Thanks to the internet many of these things can be done independently. If you look at the stats, yes many rich artists are getting richer, but the demographic of middle class artists are on the rise, and it is because they are able to do these things on their own. Now yes it would help someone to have these certain individuals, but it is definitely not necessary. The only difference is if artists plan to try to shoot to super star status in which, its not really needing these people but huge amounts of cash to spend on marketing and production, which are record labels.