They didn’t have much of a choice. In that time people had already developed jail breaks and Cydia, an app store in its own right, was thriving.

Before Apple’s App Store launched, my iPhone was running all sorts of other apps and alternative launchers.

Apple had to move fast to keep things from getting too out of control.

Over the years, as the vulnerabilities in the OS were closed and iOS added features, the need or desire to bother with jailbreaks and 3rd party pirate app stores dropped. I haven’t thought about it in many years.