If you use the app then you have to pay for their subscription to use DNS features. If you don’t pay then you’re really just limited to adblocking in Safari. The profile I linked is free and will work for all apps. It’s not as robust or customizable as the AdGuard app, sure, but I’ve never had any real issues or need for anything more. Plus it’s one less app to have installed.

It’s personal preference mostly.

It actually is a detriment because the app also download and apply quite a few filter lists that can block annoyances like website cookie policies, and way more ad categories that a simple DNS filter cannot address, and other shit like Javascript bitcoin miners