From my experience, and others, in certain circumstances this is just not true, because of the 16MB memory limitation on start-up, which unbelievably still seems to apply on Windows 2000 as well!
There is no 16MB limitation on the Registry size. I just tested an 18MB Registry. The 16MB limit occurs when the Registry and/or Gigabit Ethernet Drivers take up too much of the lowest 16MB of Physical RAM. I added the /M Patch to my RAM Limitation Patch to insure that this did not happen regardless of Registry Size or type of Ethernet.
I wasn't expecting a reply to this after two years, but thanks Rudolph!