As a user of LE, you need to implement http or DNS (or tls) challenge - typically via a tool that takes a pointer to your provider (letsencrypt). I claim that

As a user of LE, you need to implement http or DNS (or tls) challenge - typically via a tool that takes a pointer to your provider (letsencrypt). I claim that it would be less friction to simply use the same tool for verifying domain control (suplly facebook as the provider). Ed: although thinking about it, existing tools for interfacing with LE probably do too much (create certificate requests) - so might not make that much sense to reuse the tools/clients as is.