DeviantArt recently made another one of its unnecessary, harmful changes to make everyone's life more difficult; they've made it so group members, including myself, the group owner, cannot submit more than 10 images a day to the group.
For those not aware, I am the owner and head admin of derpibooru.org/, and that's what occupies most of my free time related to ponies and art. I still dedicated about an hour on the weekends to going through images on DA and submitting them here. Now, that's no longer possible, given I simply don't have the energy or time to spread this effort out throughout the week or "game the system" with alt accounts.
So basically, unless other people step up to sacrifice their free time for this group, it'll simply stagnate and die out, and you can thank DeviantArt staff for that.