> you have your details there for good and they don't go away accidentally like with the browsers.
But when it does go away (app reinstalls, phone upgrades, phone breaks etc), it causes a disproportionately catastrophic event: complete loss of access. Providing a simple email address would prevent this, but expecting the common user to have the wisdom on account recovery strategies is too optimistic. That's why many apps ask for email during registration.
That can be tolerable for Discord, because your loss is just your friends list and access to some servers, which can be recovered easily through social means. That's not possible or feasible for every kind of app.
But when it does go away (app reinstalls, phone upgrades, phone breaks etc), it causes a disproportionately catastrophic event: complete loss of access. Providing a simple email address would prevent this, but expecting the common user to have the wisdom on account recovery strategies is too optimistic. That's why many apps ask for email during registration.
That can be tolerable for Discord, because your loss is just your friends list and access to some servers, which can be recovered easily through social means. That's not possible or feasible for every kind of app.