(I've suggested ideas to increase the number of reviews, but Allmusic doesn't seem to be interested in doing so.) To be selected for a review, Allmusic's criteria are being tied primarily to pre-release buzz. So its criteria are favoring commercial music styles, heavily-marketed albums and established artists with a large fan base.
These criteria disfavor eclectic music, indie labels and new artists who aren't being heavily marketed. When Allmusic used to review albums in the past regardless of pre-release buzz, I could discover many albums (thru Allmusic's reviews) that didn't receive coverage elsewhere. For example: an archival compilation of a