The enumeration on the losing side of that debate is probably correct. But as a person who was in my early 20s in 2000, I'd like to offer what I will characterize as The Historical Context and Definitive Conclusion to This Debate.
No one actually gave a shit about that debate. Sure, it came up, but it did not alter anyone's party planning. We weren't actually celebrating the changing of the millennium, we were celebrating because we had a permission slip to do so. Any attempt to withdraw that permission was unwelcome.
In Paris on December 31st, 1999, at around 11pm local time, someone threw themselves in front of a metro. The trains were free that night (because it was the 100 year anniversary of their opening iirc), but because of that suicide, at least one of the train lines was substantially delayed. The streets from the center of the city to the north side were crowded well toward dawn as everyone chose to walk home instead of wait indefinitely in a stinky train station.
That person, who chose to end their life on the tracks that night, holds the core truth of the debate within his death: it's a ridiculous debate and those who would fight for it should just stay the hell home and let the rest of us drink a lot and dance.
You make a compelling point, for sure. There are definitely features that fall into that category (eg page transitions), there are a lot of other things coming out these days that just make life easier.
For example, in chrome (and in the spec) you can now animate between ‘height: [number]’ and ‘height:auto;’ just the other day, I had to write a python function to estimate the highest of a menu based on its length * the line height of the list items, so I could provide an exact height to animate to. It works, but it’s hacky and gross. It would be nice to have access to the solution.