You're assuming all the record labels do it distribution.
But they also do management. Without a startup that tackles the management side of things (which is pretty complex relationship wise, this includes relationships with venues and between producers and bands, just so much) attacking distribution is only half of the issue
Labels provide one or more of the following to various degrees of capability:
- Management
- Tour support
- Publicity (photos, PR, etc)
- Radio promotion
- Video promotion
- Tour routing and agent of record
- Marketing
- Distribution and Sales
- Websites, fanclubs and direct-to-fan
- Merchandising (physical and e-commerce), including distribution/sales (Hot Topic, etc)
- Art
- Video production
- Online marketing and community management
- Partner relations
- Licensing management (sync, etc)
Not all labels do all of this, it is case to case. Even labels in the same parent corp (UMG, EMI, Sony or WMG) don't do all of these. Indies vary as well.
What is the subset of these services that are (1) competitively defensible and (2) viable?
To be defensible, a major label should hold a significant competitive advantage in providing the service.
For instance, distribution and sales has been locked up by major labels for a long time because they have the infrastructure and relationships to strike deals with major retailers.
But direct-to-fan isn't defensible and websites aren't defensible.
To be viable, the service should matter 5-10 years from now.
For instance, video promotion is likely to be relevant for many years; it's expensive to produce an excellent music video and channels like Youtube mean they continue to matter.
Terrestrial and satellite radio promotion on the other hand is going to be irrelevant in 5 years.
But they also do management. Without a startup that tackles the management side of things (which is pretty complex relationship wise, this includes relationships with venues and between producers and bands, just so much) attacking distribution is only half of the issue