It's not just Facebook and Google trimming apps to help them run on lower-end smartphones. Microsoft is rolling out a new version of Skype for Android that reduces the memory and storage demands on devices running Android 4.0.3 through 5.1, improving audiovisual quality and overall speed for those devices. It should be more tolerant of flaky network connections, too. The updated app will be available worldwide in the "coming weeks."
It may seem odd to target versions of Android that stopped receiving support years ago, especially when Android Go promises to make the latest operating system more accessible. However, Microsoft is acknowledging a practical reality: many people in developing countries can't necessarily justify updating their phones every couple of years, and might even buy phones still running old Android versions. Google's February 2018 platform stats showed 42 percent of Android devices on Google Play running some version of Android 4 or 5. Microsoft can't afford to ignore low-end phone users -- it'd cut off a large chunk of its potential audience if it focused solely on recent or higher-end devices.