>There are just as many intranets out there as >there are on the Internet and their needs have >to be acknowledged.

Quite correct, but an intranet can be designed for a single flavour of a single browser as many are. When you get into the ethernet it would be nice to have at least some conformity between the various browser engines - trying to code for all possible varients of IE is a task that a lot of us no longer entertain (some code from v5 onwards, some only for the last and current iteration), let alone the versions of IE that ran on Macs. Whilst I appreciate your point about the heritage of IE (Mosaic) I still have to say that it is inevitable that at some point Microsoft will have to abandon legacy support. Without doing so their coding problems for the future (further development of IE and the O/S) are just going to get more and more convoluted and the time/man hours unjustifiable.
P.s. As an aside, the ACID tests are developed by the W3 who, most definitely, are vested interest parties to the future of web development.