An app that worked perfectly at launch does not stay that way on its own. Apple and Google both push OS updates every year. Those updates regularly break things that used to work fine. A feature that functioned smoothly last month can start crashing without a single change to your own code. Businesses that treat an app launch as the finish line get surprised later. A wave of one-star reviews arrives, seemingly out of nowhere.
Both app stores also enforce their own policy updates. Apps that fall out of compliance risk removal, not just poor reviews. Staying ahead of that requires someone actually watching for these changes. Not reacting only after users start complaining. We monitor OS releases and store policy changes as part of ongoing maintenance. Issues get fixed before they become visible problems. That proactive approach is the real difference between a maintained app and a slowly decaying one.