Why wouldn't the website be generally made using standards and techniques that allow proper display regardless of the web browser or operating system?
Yes, Internet Explorer, FireFox, Safari, Chrome etc. may have their own "quirks" (which even change depending on the version), but there are many sites that are designed to display correctly in all of those browsers.
Sorry, I just tend to see the "generally made to work with IE" comments as a bit of a cop out. Internet Explorer may be used by the majority of people accessing TechSoup, but that shouldn't be used as a reason not to support other platforms.
Thank you for passing the info along.