Apps are a big part of it. You can quit WhatsApp or Discord all you like but they're still running in background. A lot of apps are hackily built. Google is pu

Apps are a big part of it. You can quit WhatsApp or Discord all you like but they're still running in background. A lot of apps are hackily built. Google is punishing this, but let's face it, you'll still use Messenger or Slack nontheless even if they ranked terribly on the Play Store. Battery and system updates do matter. Android Lollipop basically made one of my phones unuseable. But you can try and uninstall everything and see the effects. Also Samsung phones seem to deteriorate really fast for some reason. Most of my mid range ones became unuseable after 2-3 years.