Even that could be handled, by the editor getting out of your way when you don't need it. I'm not an expert, neither in Atom, nor software design on that level, but I suppose a web based editor could have a server running in the background, doing the hard work, and a lightweight client that starts up fast. And there might be a million other ways to allow people fast start-close-interactions without actually starting or closing the software all the time.
Therefore saying that you should use a software in a certain way is not really a good argument. It's possible to adapt the software to the user.
