I think most people who post on predator sites talking about needing better bullets to kill coyotes with a 223 are rookies who probably can’t shoot. Guys who shoot Fireballs and 17s are usually loonies who load and shoot and are probably more serious hunters. I’ve never had issues killing a coyote with even rimfires, but I shoot a lot and know how, when, and where to shoot an animal.
If a bullet will consistently give 12-14” of straight line penetration while producing a 2” diameter wound it’s plenty adequate for shooting deer, regardless of what it’s shot out of. And a plain old 55gr Hornady spire point out of a 223 will give exactly that type of performance.
