Revelation has to be thinkable.
Or as Sweeney says, "I gotta use words when I'm talking to you."
If you're giving people information that's new to them you need to use language they're familiar with. For example there's no point in talking realtivity to a pre-Einsteinian audience. You can only tell people as much as they're ready to receive.
I've noted that early 20th century Afterlife narratives have almost nothing to say about reincarnation. That bothered me to begin with. After all, more recent revelations talk about little else. Why is that? Are the early 20th century communicators uninformed? Are they just spinning us a line? Not necessarily. Perhaps they're tempering the wind to the shorn lamb. Reincarnation was a new-fangled, foreign, unChristian idea to the late-Victorian, middle-class people who mainly made up the audience for these books; it didn't fit with their world view. And so the communicators made allowances- and substituted the liberal Christian concept of a hell from which the damned soul is free to work its deliverance by good works and pure thoughts. Different symbology but much the same basic idea.
Of course reincarnation may not be the complete truth either- but simply a slightly subtler way of talking about a reality that is currently beyond the comprehension of us everyday 21st century folk.
When Monsignor Benson is exploring the Summerlands in 1914 he visits a laboratory where spirits are working on inventions that will eventually be passed down the line to scientists on earth (because all our best ideas originate in Eternity.) So what are these inventions? Are we talking hoverboards? Cures for cancer? The internet? He doesn't say- or drop hints- even though such disclosures would immeasurably have increased the creditworthiness of his story.
He passes up the chance to prophesy.
Is that because he's spinning a yarn- and doesn't want to make it too easy to falsify?
Or because (as he argues himself) we're just not ready to know about these things?