You see I'm not just singling out CPK as having heavy geometry, this is almost the entire industry that grinds this way as it limits warranty returns and pictures on the internet of big blown out primary grind chips. The problem is, if you do a lot of cutting and begin looking at lower edge angles performance in a way that allows you to see what actually happens then it's clear that real performance sort of begins below 15 DPS. The DEK 3 you describe may have thinner geometry BEHIND the edge but I wouldn't and do not even grind double bit felling axes at 18 DPS. I did one for a client (I do high end sharpening work) that weighed 4 lbs., nice vintage Swedish forged double bit and it came in below 14 DPS at the most obtuse portion at just behind the apex which was a microbevel at just over 15 DPS. The owner has told me that it's held up beautifully in chopping.
The difference is obviously the axe will be allowed to thicken much more behind that 14 DPS bevel but the point remains that is all that's needed to support very heavy impacts on wood under great mass and leverage advantage. Again, if you intend to cut metal and other very hard objects then 18 DPS is fine and warranted but how many people use knives for this? There is a cold chisel for a reason, it cuts very hard materials under the mass and leverage advantage of a mallet If you do this a lot then you want a cold chisel, not a knife. In actual use even an edge bevel that is 10 DPS w/ 15 DPS micro-bevel will be quite difficult to damage as in requiring coming in contact with inclusions (staples, nails etc) in cardboard or wood and even then it is very minor damage that is just visible. Repair is swift and more importantly cutting performance is fantastic.
Again, CPK just happens to be one example of this common practice. Years ago Buck Knives came out with what they called the 2x edge, meaning it would give twice the performance and edge retention compared to a 'standard' knife edge. The only difference was this edge was ground much more acutely (around 12.5 DPS, similar to Mora grind angle). Makers have to overbuild knives because they don't know how much of an idjit the user will be, if you understand how to cut things in a smart way and how to optimize your knives then you can actually end up with an efficient cutting tool and not a 'knife-like object'.