Why does the baby monitor even need to be viewable from your phone or an app? I use one that comes with a simple screen [0], and we have 2 cameras paired to it

Why does the baby monitor even need to be viewable from your phone or an app? I use one that comes with a simple screen [0], and we have 2 cameras paired to it (one for each child). Works great and has lasted over 3 years so far. I mounted them on the wall. No WiFi, no apps, super simple. [0]: https://a.co/0Oqh3gf https://a.co/0Oqh3gf