I assume he's talking about NS4, which I'll agree is an even bigger pile than IE; IE may be nonstandard and broken, but at least it's not nonstandard and broken to the point that a simple, valid, CSS1 page can be entirely unusable for no apparent reason and then it crashes because of a perfectly valid tag combination. Why can't it just fail nicely like proper ancient browsers that just ignore CSS altogether instead of just pitching a fit over it?
Tragically, a handfull of people DO still use NS4 (~0.5%, higher for Mac sites frequented by non-OSX users), though I wish they wouldn't. I don't mind giving them an uglier page, but 100% valid XML can be so severely broken in NS4 that if it's a business site I feel obligated to go in and "fix" it at least to the point the NS version is usable, or use a hack to strip out all CSS and leave it dry.
If realityisterror is not talking about NS4, though, then somebody needs to break out the beatin' stick.