With Cloud9 they can develop on any computer they have access to, whether their's, a friend's, or even one at the public library. It is just one less barrier to being able to engage people.
I've run into the use case while traveling abroad where I don't have a computer (out of paranoia / lack of security).
Internet cafés are everywhere but setting up the perfect dev environment takes so long... so far it's made development fairly impractical, especially because they're often very old Windows machines. I've had good experiences with C9 so far, though I'd like to see how it pans out under that use case.
It is a Not Unreasonable (TM) time investment to automate setting up your dev environment in the way you would a prod environment. emacs.d and other dotfiles in source control, masterless Puppet or Chef on your laptop, etc. If you're willing to go as far as installing Vagrant manually, the rest can be made pretty easy.
Of course, this works too.
Developers with tech jobs should also be able to afford high end machines.
It's totally worth it, if your employer will allow you to work on your personal machine at all.
Interesting that for me it was the startups that provided good machines while the enterprises provided 4 years old lenovo laptops with not so good batteries not the specs needed to use a VM effectively
Yeah, well, I'll just add that to my (very long) list of reasons never to work for enterprise companies.