IMO, this is an overly general and somewhat misleading "blanket
statement". The TeX--XeT model has its limitations, certainly, but there
are plenty of RTL documents for which it is perfectly adequate. Not
every document requires mixed-direction math, or \special-based colour
and hyperlinks wrapping across lines.
True but most people these days desire to create fancy documents (containing color, hyperref, etc). The color is not that bad in XeTeX since you can use color as font feature without the problems of \special.
-------------------------------------------------- Subscriptions, Archive, and List information, etc.: http://tug.org/mailman/listinfo/xetex
