I think one other thing to point out for that CX5 in the video, almost 100k miles in 2 years.
I'm just guessing, but I bet it saw a lot of highway miles, just 'loping along' on the freeway at constant speed/rpm.
If that's the case, I wonder if it sees more buildup because it doesn't get a lot of heat in the cylinders, you know, the 'ole Italian tuneup. I know that's not as much of thing with cars built in the last 30 years vs. the old carburetor days, but I think there is some benefit to wring it out every once in a while.