Dear llt
I like your comment, it’s an interesting point to consider, especially the reality of early monastic life being much more about memorising the Dhamma. It got me reflecting and I feel has led me off on a tangent which somewhat relates to your comment and perhaps (I hope respectfully) disagrees with some of it.
Perhaps memorising the Dhamma became more important after the Buddha passed away.
I have a notion that during his lifetime, things would’ve been more in flux.
Also, perhaps the life of a householder at that time was less cerebral and more conducive to being present to the realities of life. Thus perhaps it wasn’t the lack of literacy (as we know it), so much as the clarity and presence to reality and nature that may have existed then, in a way that it does not, now; unless of course you live, very simply and purely as a householder.
I suggest that the householders of the Buddha’s time had a far better chance of attaining any stage of enlightenment, than we do today. Today, we have Sutta Central, books and talks about suttas and we spend endless hours trying to work out what it all means. Surely in the Buddha’s time, they didn’t have to think about it so much and figure it out so much, surely the language used had to have been ordinary to that time and place, meant to speak and relate directly to things known in daily life. Simple and clear and able to go into those illiterate minds, basically, deeply and “un-cerebrally”; those minds that would’ve been so much more present to their lives, their deaths, the seasons and things that were real and concrete and tangible and emotional and clear. The reason I think this is because of the agrarian nature of those societies. Surely, being close to nature and being unable to control and keep thoughts through writing, would’ve freed them up to be present to and closer to nature and particularly to their own nature - their bodies and minds.
So perhaps they didn’t need to memorise whole heaps of stuff. Perhaps it was enough to hear the teachings a few times. Also, I imagine, (going on what it’s like to be around monastics today who inspire me) that it would’ve left an indelible mark on your mind to have been taught by the Buddha himself, or even one of his enlightened disciples. Such experiences probably amply balanced out the lack of modern literary conveniences
Thank you for your comment llt, it sort of stirred the pot and perhaps a notion that you hadn’t intended, presented itself to me!
I’ve noticed that often on online (or indeed any kind of written dialogue) forums like this, we often think we’re interacting with each other. But actually we’re interacting with our own reactions to the written words we read. Thus I want to make it clear, that I write this to you with great respect for you and great well wishing for you and a sense of gratitude for all the differing and respectfully and fearlessly expressed opinions here. It’s nice that we all create as safe and as welcoming a space as possible. 
With metta and thanks.