you could, but unfortunately the LE certs have a very short lifetime, and renewals are a thing so you need a master server to handle the renewals, periodic syn

you could, but unfortunately the LE certs have a very short lifetime, and renewals are a thing so you need a master server to handle the renewals, periodic sync, and to handle the case when the master goes away this would be considerably more complicated than having a second independent certificate (assuming you've automated the entire frontend provisioning process)