The "2019" version also covers Visual Studio 2015 and 2017. Microsoft unified the version numbers. So if you install the 2019 package, you generally do not need the separate 2015 or 2017 packages (though many installers still install them for legacy reasons). Why Doesn't the Program Include Its Own Files? Great question. It comes down to efficiency and security.
Each major version is binary-incompatible. An app built with Visual Studio 2010 cannot use the 2019 redistributable—it will simply refuse to load. 2019 c++ redistributable
Most users click "Next" without a second thought. But sometimes, the installation fails, or a program crashes with a "missing VCRUNTIME140.dll" error. The "2019" version also covers Visual Studio 2015 and 2017
If you’re a gamer or power user, ensure you have the latest versions installed from Microsoft. If you’re a developer, always bundle the correct redistributable with your application’s installer. Why Doesn't the Program Include Its Own Files
In the early days, every program shipped with its own copy of standard C++ libraries (DLLs). This led to "DLL Hell"—where one program overwrote a shared file, breaking another program.