I think you're overestimating ordinary people's ability to understand their language's forerunners. An English text from the 11th century is nearly impossible to understand except for a few words for all but the ones with the right education. Modern Farsi and Middle Persian is separated by more than 2000 years.
Actually, nevermind, I found a comparison of a Middle Persian text and a modern translation and they looked surprisingly similar. I shouldn't make assumptions based on my experience with my own language and offer uninformed opinions. Sorry.
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