He talks about enterprise web software, not so much public sites/blogs/etc.
The timesheet and employee self-services system where I work are IE-only for no good reason. The timesheet site is a Java applet, and the employee self-services system uses XML and Javascript to render content. There's nothing I've seen on either system that cannot be done using simple web standards. I guess people who use Macs here (and there are a number of them) have to have access to a PC to get paid.
As long as we allow enterprises not to be standards-compliant through and through, we, as web developers, will continue to have IE-related headaches.