not the part where they actually released it and not electron aka atom shell

It was released. It was on a growing number of webpages and an important part of the Dev Tools of IE9+ (also giving them a massive install base from before Atom existed). If Atom didn't build Electron what became the VS Code team might have built something similar on their own eventually (though it probably would have been IE-based and Windows-only in that alternate history). It truly seemed convergent evolution at work.