I'm pretty sure Emacs came up with this idea: "embrace and extend" TECO.
They seem to want everyone to make Chrome apps, not web apps. If that happens, ultimately we all suffer from the loss of an open web.
Stallman seemed to want everyone to make Emacs apps, not TECO macros. If that happens, ultimately we all suffer from the loss of an open TECO community. (How is a Chrome/Chromium App different from a Gtk3 app or a Tk app? Those aren't open standards. They're just libraries the authors wanted to write and to share with the world. Not everything needs to be a standards process, sometimes you just do something and see if anyone likes it.)
More seriously, there are quite a few differences between adding a feature to an open-source project and adding a feature to a web browser shipped as an inseparable component of the operating system installed on 99% of personal computers. As a thought experiment, imagine you want to use some dongle you just bought. There is a driver that comes with Windows, but you use Linux. Do you think you'll be using your dongle anytime soon? Probably not. But imagine the driver comes with FreeBSD instead. While you probably can't use the driver code verbatim (different APIs), you can probably port it in significantly less time than it would take to reverse engineer. So while FreeBSD may have bypassed the standards process for supporting that dongle, it still works for you with very little effort.
I think if you're going to get outraged, it should be about how much memory Chrome uses, not that websites can now have prettier notifications when running under Chrome.