Promo is still important. Schoolboy Q had plenty of promotion, especially compared to his last couple albums. Now the kid cudi is something different thats really pushing the 'no promo' line.
However, really this whole thing is a sign we are starting to return to actual consumer interest driving label priorities instead of label priorities trying to drive consumer interest. The label priorities angle works in pop music and megastars but more and more for other genres that arent as overwhelming popular, the labels are finding its better just to release a lot of music with tiny budgets, and then when something is successful on its own merits you put your money into promoting the NEXT single/release from that artist.
Honestly people forget, touring used to be the promotion, used to be a new rap album came out, you just saw stickers, posters, and the label sent a new pair of timbs, some hoodies, and t shirts to the DJs along with the music kit. The magazines etc would get some interviews and photo shoots. That was the bulk of the promotion expenses.Labels wouldnt even worry about pushing an artist to radio until the song was already a 'hit'.
That method generally leads to much better music quality, because the fans actually choose the hits, not the 'tastemakers'...