A basic LEMP stack (Linux, Nginx, MySQL, PHP) is mostly easy to setup and configure and is nothing to fear. Usually once you look into some existing solutions in Ansible, Chef, etc you see how simple they really are.
There are things to be concerned about like security, but usually it’s not too complicated either in terms of locking down ports, access, SSH etc. Once again there’s default “cookbooks” to help with this.
The absolute best part of configuration management is just being able to destroy/create servers and know that every time you start one up, you’re getting the exact same consistent setup from scratch.
Another potential benefit is having 1 cloud server PER client. A $5 Digital Ocean box is probably powerful enough for most standard client WP sites (with proper caching). You can still easily up-sell that at a bigger multiple and it has many benefits. You don’t need to worry about taking down ALL your sites if something happens to 1 server.