I am sorry you missed you flight. But I don’t feel that PAX lack of preparedness is not indicative of just NW. I am equally positive that there are hundreds of PAX daily who for whatever reason will miss their flights on different airlines.
I realize the importance of making my flights and know that at the end of the day it’s my responsibility to make them and laying the blame on some one else is not an option.
In over 15 years of weekly travels I have yet to miss a flight, but then I always make sure that I am there 2 hours early too. With the amount of traveling you do, I'm surprised you took this stance.

Happy travels.