Now, as I work most of my time as an AV-tech, I'd have to say that this is truth with modifications.
Projectors at conferences are usually vga only. I've never encountered a DVI cable in static systems at conferences. Sure, when we set it up ourselves and go for high quality HD projectors @ 10k ansilumens we will use our nice fiberoptic dvi cables or hd-sdi, but most of the time it is vga/rgb-hv.
That means one(1) adapter, if you bring your own laptop. Even peecees come with DVI these days.
For us techs, it means 3 adapters, one dvi-vga, one minidvi-vga and one DisplayPort-vga. This will not make much of a difference in our flight cases...
Apart from that, I agree. Apple pulled a bit of a stunt with the DisplayPort. While I like the new port, I think it's way too arrogant to assume that people will ditch a 6 months old machine just like that.