Would you mind to elaborate how A (the ability to intercept traffic) leads to B (the ability to make Let’s Encrypt issue a certificate for the (any?) host? I fail to see the connection
https://nitter.lacontrevoie.fr/rmhrisk/status/15749933380840...
Edit: If you did this, it would be show up in certificate transparency logs. So a very alert sysadmin could catch you in the act.