AFAIK all modern browsers offer the ability to turn off JavaScript globally. Add-ons such as NoScript for Firefox give you more control though. I use NoScript to have all JS disabled by default on a page, and turn on/enable specific sources as necessary. On zencastr, I noticed that the page wasn't loading so I temporarily white-listed the site, and it is visible now.
A common and, IMO not-unreasonable view is that all content on the web should be viewable on the web with just HTML and CSS (sometimes even without the latter) and thus JS should never be required save for specific tasks such as in-browser computation and the like. That's a bit extreme for me, so I just white-list scripts as needed.
I use NoScript for security reasons. I find that I usually only have to turn on 1 or 2 scripts to get the content on the site to show. If even that as many show it without scripts. It's a tiny percentage, often using fancy crap underneath, that absolutely require JavaScript to even see static content. I don't loose much ignoring them but gain plenty in security, loading speed, and battery savings.
Will you though? What's the cost of the extra development and maintenance you'll need to do to cater for such a tiny sliver of the population, many of whom will just whitelist your site if they're interested in your content?
Around 1% of users run linux. If you have a commercial videogame, you will lose money and users if you don't think about this.
Now consider the ROI. I'm a full time linux user myself, and still I understand when someone says 'sorry but such a small market share is not worth bothering with.'
