I can see that as being partially true, that's why I always use a oiled foam cover over mine. When I was a kid driving my big lifted Chevy I used a the normal chromed top and bottom covers with a six inch tall open element in between. I did a LOT of deep river running with my truck and could easily drive through 5 feet of water for extended periods of time. We rode the Black River in Lesterville MO for many years until trucks where kicked off it for the most part in or around 1987.
I remember hitting the water and blowing water up over the cab of the truck while trying to soak the other guys inside their trucks. it was sort of a game of jousting with water. Very, very seldom did I ever have issues with water getting past the foam element and causing hydrolock. Of course, that's not dust.
I can see a diesel truck having issues. They use a LOT more air than a gas engine does. That's why OTR and most off highway equipment have two separate filters and a HUGE filter box. So comparing the K&N filter on a diesel is to one on a gas engine is not comparing oranges to oranges. Neither is comparing a turbo'd engine to naturally aspirated.
It's obviously your choice but until I see real flow meter tests with a way to determine the amount of dust that has made through the filter (not just the amount that it's caught) I think I'll stick with the pleated cotton filters. For two reasons, I don't play on a dusty roundy round track, and honestly, how long will any one person keep their vehicles? Mine are usually kept about five to six years. And I seldom buy new vehicles anymore because I like to drive my own vehicles, I don't want or need a computer to do it for me. One more thought, if 90% of your driving is on pavement, where's the dust?
I used to be obsessive about keeping my air filters clean when I lived in the urban areas, replacing or cleaning clean filters was a must because the manual said to. I finally realized it was the aim of the company to not really suggest that because it was necessary, but to ensure that parts where sold, hopefully bought from them.
Unless the vehicle is used in some sort of extreme conditions (off road in dust, in water with a paper filter, or racing) there is really very little need to replace or clean an air filter as often as is suggested. Just my experience... YMMV.
BTW- The engine in my old 78 1/2 ton short wheelbase Chevy K-truck was a very well built 355 (not by me but for me), it ran on 39/15-15 MT Baja's (old style bias) tires with a 6" lift, traction bars, granny low 4-speed, 205 t-case and a rear limited slip. The rear was a 14 bolt because 12 bolts could just not handle it on the street, I ripped a couple apart before I got wise, and the front was a Dana 44 (not a corporate 10 bolt).
The engine in my current 75 Chevy is also a very well built 355 (also not by me). Both were built by what I call speed shops that do that sort of work for racers and they cost a lot of dollars, with a lot of good quality parts and attention to detail. It's still a project in the making however. I might end up pulling the engine and chucking the truck and find a nice old CJ7 to put the engine into.