If you want a full-fledged system, you use GNU/Linux, or probably a distro like Ubuntu.
If you want a full-fledged system from Chrome, you use the Internet.
You can text edit with sed, but that's not how anyone uses Linux, in real life, right?
If they included sed and intended it to be your text editor, as ChromeOS has included half-assed local picture and video playing (is this not what those things are for? Am I supposed to be using these things for stream manipulation, not picture/video viewing? Because if that is the case, their UI has failed to convey that.), then I would without hesitation assert that their distro was poorly considered.
A Chromebook without the Internet is ludicrous, because no user operates like that.
They might have been better off to not have the local picture and video player. They're the embarrassing "Notepad," if I want to make the analogy to Windows, again.
I don't believe that anybody doesn't. Even android phones have better offline capabilities (Way better, and generally with less offline storage to boot) and people expect their phones to always be online.
Here are the devices I own that are always online, when they're on:
TiVo, Logitech Revue, Wii, Chromebook, Android 1, Android 2, iPhone, Desktop 1, Desktop 2, Laptop 1, Laptop 2, Laptop 3, Laptop 4, and Kindle Fire. (I might be missing a couple.)
I expect my Chromebook to ALWAYS be online. Not least of which, because my Chromebook has 3G, just like my first Android phone did.
The job of fmt could be done with sed, of course. As many of HN'ers know, sed can perform the functions of many other UNIX utils. If used as an "all-purpose" program, perhaps it raises the possibility of the typical mantras about "the right tool for the job". But consider this: editing/transforming text (e.g. output from other programs) as a "job" is somewhat all-encompassing under UNIX. Everything can be a "file" and every file can be represented as "text" (e.g. ASCII, hex). What varies is the context in which you do this job of editing/transforming. It might be preprocessing source code (text) for gcc or maybe it's preprocessing a resume (text) for groff.
"When all you know is a sed, everything is a text." - Unknown