The instructions make it clear to install it on a clean VPS... so why add non-Cloudron stuff? The reason is not "control", as in Cloudron wants to control what you do with your VPS. That line of thinking is like saying, "Hey, this is MY laptop and I want to use it in the swimming pool to keep cool." The laptop manufacturer isn't going to stop you from doing what ever you want to do with your laptop, but if you want it to work, then follow the instructions!
Plus, if someone goes ahead and starts adding this, or testing that, and something will break, then they are going to come here and, at best, ask for help and take up time from actual legit problems, or at worst just complain how Cloudron doesn't work.
Clean VPS for installation. Keep it Clean for continued functioning.