Well, I am just speaking from my experience, real world, not "internet theory". My experience is of a dozen cuttings, one summer season. So really my experience is in the range of anecdote, rather than "scientific proof". Though to disprove a theory, an anecdote may suffice if the theory can not explain the anecdote. So I have had success with cuttings from aerial roots.
I do not recall any "rule", by any author about aerial roots not being useful for root cuttings. I've seen "off the top of the hat" speculation, but recall nobody with significant experience beyond a one off anecdote speak to the subject.
I have found success with cuttings varies wildly, depending on season and depending on how consistent I am with my care. I have had branch and other cuttings fails at times, and succeed at other times. All from the same Ficus. I have best success in middle of summer. Other seasons, are not as successful.
note: Aerial roots tend to be very straight, linear without movement for the above ground portion. This means there is little advantage to using them as scions from which to strike cuttings. Root cuttings are only used when there is attractive movement in the piece of root used to strike the cutting. Otherwise a branch cutting would suffice.
