It's already painful to get Let's Encrypt set up in a web farm scenario. This won't make it easier.
You just don't stop answering challenges until the cert gets issued.
I don't know why anyone would have stopped answering challenges after the first request anyway. Surely the default assumption should be that everyone has network & processing failures, and hey maybe ACME would need to check again if something broke before the cert was signed.
Besides, your argument could be used to justify any price hike! "If you can afford X, then you can afford Y!"