That's interesting to know; perhaps it was just the right time for independent discovery.
Still, a web-based code editor on its own has independent utility from an IDE. I'm not sure they would've taken the plunge into a full-on Electron IDE without Atom first showing that there was demand for one.
Monaco was already embedded in the IE 10+ Dev Tools before Atom, and Browser Dev Tools are IDEs in almost every respect other than being bundled independently from a Browser, and even that has changed in some recent respects (you can run Chromium's Dev Tools as an independent app).
(In an interesting full circle, the Elements for Edge plugin to VS Code makes VS Code a full DOM browser for Chromium-based Edge.)
