I think this is a classic problem with alternate music platforms in the Internet age. With all the services based around and using the prevailing media industry (Pandora, Spotify, iTunes), which all happen to be "good enough" to the average user, how does one convince said user to try alternate methods/services and alternate artists? I think it's a very hard line to try and encourage the populace to cross themselves if they don't already want to do it. It involves a bit of a genuine philosophical stance on how artists should get paid and how distribution should work and most people just don't care that much to look into it.

You are right, it's probably easier to find an app in a store that has a total of ten apps then one that has hundreds of thousands. But on the other hand such a store has a lot more visitors then your own blog, so if your content is good and gets discovered then you might be able to sell a lot more then on your own blog.

From what I know jamendo licensing is a stock music websites that does not require you to be exlusivly on their platform.

So this means that they could still keep their music on their own website and distribute their music directly to their visitors but also offer their music through jamendo to a much broader audience.

I would recommend them to give it a try, it won't cost them much effort to read the jamendo legal stuff, then open an account and upload their tracks. Some months later based on the stats I would decide to stay or leave, because its hard to know if something will work for you if you don't try it out.