I'd say "most developers" already have a box running some kind of website where they are doing this anyway, but even if you disagree I think you have to be willing to cede "many", especially given how many people who use GitHub are currently doing Ruby on Rails or node.js work. I'd even go so far as to say that those that currently aren't /should/, as the experience being a sysadmin is important when understanding how other sysadmins will react when they see how your software is deployed, which I guess is another topic of discussion that comes up often here (oft filed under the "Debian vs. Ruby" banner).

(Part of me is wondering if many of the more controversial discussions on this site are between people who have sysadmin experience (and considered it valuable) and people who don't.)