Most if not all apps on phones will require you to sign up and your date is out of your control as it is not hosted by yourself. Plus you are usually limited to doing everything on your phone which is a pita.

Selfhosting is a way of life. I enjoy providing services to myself and my family that I control with the peace of mind of knowing that data stays with me. And it's fun doing it too!

My guess is once you start selfhosting yourself, you'll eventually come to the same conclusions.

However, selfhosting isn't without it's dangers. You have to ensure you have backups of the data. You are also responsible for securing it and you have to maintain your infrastructure as well