There's literally zero work with Caddy. I'm not sure I understand what you're trying to say.
Also, there's massive advantages to having TLS issuance built into the webserver, such as proper OCSP stapling, having an active process to trigger renewals as soon as a revocation happens (hearing about it via OCSP), solving the ACME TLS-ALPN challenge without extra steps, and unique features like On-Demand TLS that many SaaS companies are relying on to provide a custom domains feature to their customers. None of those things are possible unless it's tightly integrated in the webserver.
Also, there's massive advantages to having TLS issuance built into the webserver, such as proper OCSP stapling, having an active process to trigger renewals as soon as a revocation happens (hearing about it via OCSP), solving the ACME TLS-ALPN challenge without extra steps, and unique features like On-Demand TLS that many SaaS companies are relying on to provide a custom domains feature to their customers. None of those things are possible unless it's tightly integrated in the webserver.