On the first hand, I really appreciate the 30 - 40 hours of battery runtime my Pixel 5 has now. Restricting background apps is a big part of this.
And then maybe "what app a user selects", if the user manages to follow the procedure.
The only way to run an app non-stop is to have a persistent notification. And even then, apps are killed off left and right by the likes of Samsung. See https://dontkillmyapp.com for more details