This is a technical decision some developers make because they're well versed in Javascript, or because their business can only fund the management of one codebase, or because there's libraries that add massive convenience functions to their development. Or because they believe that their UI needs to have a consistent experience. Or <insert reason X, Y, Z here>...

This whole article is about Chromium and Electron. I am not sure what the purpose of your question is.

Assuming the glue code to the native OS (i.e. things like actual local file access, access to hardware, raw network sockets) has roughly the same interface across all the major platforms, you only need one code base and it will run on anything capable of running a web browser - phones, tablets, fancy tablets and other embedded devices, all common computer operating systems, game consoles, whatever. All the hard work of maintaining a common runtime environment is abstracted to the underlying browser framework, and the best is, whenever the browser framework gets ported to some new platform, your app will get support for that platform as well for virtually no effort and expense.

I get why people are upset at that (especially the sometimes significant performance issues), but I also get why many applications went down the "Electron everything" route. In the end people who know C++ well enough to be able to deal with cross-platform bullshit are expensive and coding for cross-platform is a nightmare. There's a reason why there aren't many "top dogs" left.