"Please explain how monasticism can be said to be vibrant when it spiritually benefited only the few while keeping the people in ignorance and superstition."
Well, monasticism is the crown jewel of The Church. It may very well be that the monastics of the Church today as well as in the past, in their unending prayer, are exactly what keeps sin from totally destroying the world, but that's another discussion. In any event, it wasn't the monks who kept the people ignorant and superstitious, at least in the East. And out there, as I said, things were different than in the West. For starters more people could read...and did. It may well be that The Church in the West kept people ignorant. That simply isn't true for the East. try not to be so Western Christianity arose in the East and spread to the West. You think about it with the mind of the "Enlightenment", but that isn't where it came from at all.
If you have never walked in a country with a people who are at least 95% Christian, you can only imagine the difference between life there and here. I have spent time walking in such a country, where monastics are everyday sights on the streets, and where the very air itself is filled with the love of Christ.