You are speculating without justification. Re-reading having no/lesser benefit (a highly-suspect conclusion, given the massive sucess of spaced repetition), says nothing of the benefit of reading once + writing once.
Recording and retaking the notes from the audio/snapshot is actually reinforcing the knowledge twofold, one is recalling the info and then rewriting it. I don't know if this is for everyone (most likely not) but it did work well for me.