Wilder also had a bunch of consecutive title fights without being knocked down. Doesn't mean that much tbh.
Wilder was mostly fighting journeymen like Szpilka, Duhaupas, Molina and Washington, and avoided the better heavyweights for years. Klitschko fought 15 boxers who were in the Ring top ten, everyone who was available. I doubt Klitschko would have been knocked down by Cunningham and Ngannou.
He got knocked down by a low level journeyman called Pannell, who'd very likely lose to Ngannou. And KO'd by a tough journeyman in Puritty.
That's because his whole style was "grab n hold" with the occasional throw (Povetkin). And I doubt Fury would have lost to anyone Wlad fought, let alone get knocked out by a couple of them. The closet Fury ever got to being KO'd was Usyk, who is arguably one of the best to lace them up since Ali.