@az 'agency' can mean many things, from speaking tour authors or vaudeville animal acts to, yes, an Indie label. Book publishers or record labels have a bigger problem of having 'units' to ship, agencies manage bookings.
They have common need to
- showcase specific offerings with bios, galleries, news &c
- take inquiries into bookings for each
- present upcoming engagements for each
- publish online and echo to social media
Probably other things too, but that's the minimum.