And they shall give heed to that which is written, and pretend to no other revelation; and they shall pray always that I may unfold the same to their understanding.
Beyond these basics, our canon of scripture contains very little about the spirit world that follows death and precedes the Final Judgment. So what else do we know about the spirit world? Many members of the Church have had visions or other inspirations to inform them about how things operate or are organized in the spirit world, but these personal spiritual experiences are not to be understood or taught as the official doctrine of the Church.
Many members have had personal revelations about the spirit world, because very little detail on the subject is contained within, as D&C 32 calls it, "that which is written." But if we're not to pretend to any other revelation—because obviously there can be no insight from a non-scriptural source unless it's pretend—then why is Oaks legitimizing people who have received revelation about non-scriptural concepts? Sure, he doesn't want those people sharing what they've learned, but he's not saying they're fake revelations—he's just saying they're personal and should be kept private.
So who do we believe? Joseph Smith or Dallin H. Oaks? And why should a church that claims its god is the same yesterday, today, and forever even present us with that dilemma?