> How well would it scale for a musician to personally handle depositing checks from millions of fans?
Like many scaling problems, that's a good problem to have: at that point, you can afford to have people working for you depositing checks, which is pretty much the inverse of the power relationship artists have with labels.
> the inverse of the power relationship artists have with labels.
You don't know what the relationship with the label is. Some artists come in with their own label and only need distributor to reach a bigger audience (artists $$$/labels$$). Some come in completely unknown and the label has to front all the money (artists $ / label $$$$), and some are quite happy to be on a smaller label and let the label handle the business side of things.
> at that point, you can afford to have people working for you depositing checks
...and paying royalties for samples, collaborators, songwriters. Well now we have to hire a guy to handle all of this and you can either pay him/her a salary or a cut of the sales. Now we've slipped back into the label distributor problem.
Like many scaling problems, that's a good problem to have: at that point, you can afford to have people working for you depositing checks, which is pretty much the inverse of the power relationship artists have with labels.