"An English medieval proverb said that if the abbot of Glastonbury married the abbess of Shaftesbury, their heir would have more land than the king of England."
Not really, quite many monasteries themselves ended up very wealthy. Though they could have acted as proxies by churches. But did not mean they did not hold land what was the wealth back then. And did not have to divide it as inheritance had to.
> You might be confusing "monastery" with "church."
Many religions besides the catholicism have monasteries, and exploit the same social loophole. Countless Buddhist monasteries also operate as a spa hotel of sorts.
https://en.wikipedia.org/wiki/Dissolution_of_the_monasteries