They only hooks I don't de-barb, are ones I use for bait, such as when targeting catfish. The barb helps keep the bait on the hook. Otherwise, I'll mash down barbs, even on trebles I use for big saltwater lures. I have yet to feel that I've lost a fish due to a de-barbed hook. Not saying I don't lose fish, just that there is usually another reason.
I've even tested the de-barbed hooks with hooked fish by intentionally giving slack & very few have tossed the hook. Those that have, as far as I could tell, were not hooked well to begin with. Not saying it can't happen, and certainly some species of fish are more difficult to keep hooked than others, but a solidly hooked fish is often not dependent on the barb to stay hooked. Proper fighting technique will improve your chances of not losing fish, but it still can happen.
If you're de-barbing hooks, take great care not to damage the hook point! It can happen, particularly with light wire & smaller sizes. Test them, make sure they're "sticky" sharp & remain that way. I test every fly as I begin to tie it to my tippet! If it's not sharp, it doesn't get used, or I'll sharpen it then depending on the type of hook.
I had a fellow many years ago tell me that he doesn't use barbless or de-barbed hooks because he lost too many fish. Then I fished with him! He never checked the hook point after continued use, & wouldn't change flies!
We were fishing for bass & both using flies tied on Mustad 3366 hooks. They're not particularly sharp to begin with & not a high quality hook. The point on his fly looked like it had been mashed with a hammer!
Hooks do get dull in use, and if they do, don't expect them to penetrate as they did when new!
Won't matter if the hook has a barb or not, don't get a good hook set for any reason & you're going to lose fish!