See, to me, this looks so much easier.
I mean, I guess I'm biased 
but even accounting for the fact that that's the type and brand of tin opener I use myself while I've never even contemplated opening a tin with a knife, the tin opener seems less dependent on technique and correct angles and paying constant attention.
And I never have a problem with my tin opener having been used for slicing chicken so not being clean when I need it, or someone being upset that I've spoilt the tin opener by opening tins with it, or getting distracted when making the first thwack and skidding a blade into a valued appendage, or dealing with those hazardous-looking raggedy edges all over the lid and lip that'll stop the food sliding neatly out.
Although perhaps the guy in the video you linked is actually just bad at it, and your results are much neater/less disconcerting
I'm not trying to be obtuse, I just don't understand what's more difficult about it than using a knife. Unless maybe it's something to do with the coordination of clamping and rotating, like patting your head while rubbing your tummy? I do know what it's like to struggle with something that other people think is a piece of piss while having no problem with something that's supposedly difficult, but surely any particular aptitude for coordination that might be required for using that tin opener, you'd need as much or more with the exhilarating freestyle knife-wielder technique? Or maybe it's something like a cultural difference, and the things I value in a tin-opening experience are not the same things you value.
I also still don't get how your DH gets through so many tin openers. Maybe you might make the mistake once of buying an ultra-cheap one and having it rapidly conk out — or obviously someone who's really struggling for money might not ever have £10–15 spare all at once to chuck at a fancy tin opener. But even splashing out that much on a swanky branded Dutch tin opener is fairly affordable in the grand scheme of things, given you only need to do it once IME. I bought mine twenty years ago, I probably don't clean it as much as I should, and I've never done any maintenance tasks on it. But it still works perfectly every time with little effort or attention needed, and it probably cost less than a tenner. Judging by the pricing in old Argos catalogues, my parents would've paid about £2 for their similar perfectly-functioning tin opener 40 years ago. I'm struggling to work out how you could break it, short of bashing it with rocks, spraying it with saltwater daily, or maybe using it as a spanner.
And the other thing I'm confused about is that if you only ever use the designated tin-opening knives for opening tins, why does your DH complain about you making the knives blunt? Or are you just a scapegoat for the fact all the knives are blunt from never being sharpened or honed, except by dragging them against another knife (most likely of equal hardness, and therefore pretty ineffectual)?