I think that when people say there is no such thing as down time or quiet, slow periods anymore, it's true and it's not true all at the same time. I don't think it is a statement that can be disregarded, because a lot of the crowd analysis is subjective and based on personal perspective/perception. Chances are, most of us are not looking at actual attendance numbers and stats on how many people are in the parks on a given day when we deem a period of time at DLR as crowded or not crowded. Instead, we are using or own internal barometers and gauges to determine what is too crowded or very manageable for us and our own personal tolerance levels.
There are days when some of us might be in the parks and think that the crowds are totally fine and tolerable. Someone else might be in the parks on those same days and find that the crowds are too much to handle. Everyone has their own tolerance level. I've seen people say that New Year's Eve at DLR was not that bad, whereas other people found the crowds to be way too much to handle.
All I know is that this is not the same Disneyland that I grew up with, where -- back then -- there were actual extended chunks of time when the park was slow, and other times when the crowds were ghastly. These days, Disney makes a point of trying to offer special events or attractions during times when it might be slower (like Frozen Fun, for example), with the intention of luring in more people.
I'm not saying that the parks are wall-to-wall packed every single day of the year, but I honestly do think that the extended chunks of "quiet" days have lessened and become fewer and far between.
Also, weather plays a big role. if we are having a crazy, out of the ordinary heat wave, that can keep people away. if we are getting pummeled with heavy rain -- or if there is even a good chance of rain -- that can keep people away (and El Nino weather is supposedly coming this Winter, so that will definitely have an impact on crowds). If there are no weather situations happening, but the Halloween Time season and/or the Holiday Season is going on, there will be a lot of people on many days, as those seasons are extremely popular. Holidays (Veterans Day, Columbus Day, etc.) will put more people in the parks as well, simply because a lot of folks are off of work and school.