What kinds of devices are you referring to? (Remember, we're talking about the days before mobile was a big enough market to justify making mobile versions of websites.)
Do you mean Blackberries? I'd humbly submit that, from a business perspective, Blackberry support wasn't an important goal for many sites.
Or do you mean laptops? There was a long time when mobile wasn't big and just about every laptop supported at least 960px.
> You don't need to have text fill the entire width of the display to have a site work everywhere, I don't understand why you brought that up at all.
I thought you were suggesting that the pre-mobile, 960px technique was bad for large screens. It sounds like I was mistaken, and you're actually referring to smaller screens.
Everything from monitors to PDAs to laptops of various form factors. Even as late as 2007, 20% of displays seen in web stats were 800x600 or smaller. There were also plenty of devices that could have accessed the web but people didn't bother because the web was so broken with IE 1024 crapsites. The iphone happened in 2007. There was no period where the number of people getting boned by fixed 960px sites was insignificant.
>Remember, we're talking about the days before mobile was a big enough market to justify making mobile versions of websites.
That is begging the question. You can't assume X as a premise to demonstrate X. 20%+ devices were smaller than 960px. It took (and still takes) no extra effort to design a website correctly rather than with a fixed grid. Just as it took no extra effort to design a website correctly rather than for IE only. It is not a co-incidence that "best viewed in IE 5" and "best viewed in 1024x768" buttons were best buds. Both stem from the same source.
However, as someone who was a webmaster in 2007, I can tell you that the 20% figure was not even close to true for my particular sites. Other webmasters I knew told me the same.
So I'd say that this, like all things in web design, admits of no hard-and-fast rule. Rather, the answer is "it depends." In 2007, it depended on what your analytics were telling you. Most sites nowadays have a strong business need to support phone-size displays, but even today, not every single site does.
This sounds fairly obvious doesn't it?