Found the announcement I was talking about in 1998. It’s here: https://www.hornet.org/info/demonews/other/the_day.txt

“We have been carefully dancing around the issue for years. Now it is
time to confront it directly. The PC Windows Demo Scene. It is a scary
thought. Real PC demos produced to run under Windows only with no DOS
compatibility? Blasphemy. Or is it? The world IS moving to a Windows
environment and it seems only natural that our scene will follow.”