I've mentioned them before; there are no artists under that umbrella, ASoS just manages the releases from a great many different, mostly newer artists.
Considering their latest release, Biscuit (showing their colonial allegience, as that only means something sweet if you're from England, or in their case Down-Under) is free to download, and their entire discography can be downloaded in one fell swoop for ... one USD, this action wouldn't be about money.
As stewards of these songs from relatively unheard of (sometimes anyway) artists, they probably felt compelled to white-knight on their behalf.
But there's no advertising money to be made housing your songs on bandcamp, and considering a person could offer TWO WHOLE DOLLARS for a 90-track album, there's no money to be made selling your music on bandcamp either. Their choice would have been about noosphere; about being a name you've heard of, might think of later.
But this decision wasn't up to the individual artists, because the managers at ASoS are responsible to protect their 'brand' and there are few other means of doing it besides the atomic banhammer of the DMCA.
Unless it was the string-pulling of the lizard overlords trying to destroy what's left of Pony before anymore slaves escape. But there are simpler explanations available.