For me, the promise of Caddy and especially tools around it like FrankenPHP make the "everything in a single binary" idea the MORE enticing option, not less.

Sure we already have repeatable infrastructure, containers, etc. but I also love the idea of just building and shipping a PHP app binary that includes the webserver. It makes server provisioning even less of a priority, especially if I have reasons to not use serverless or PaaS tools.