Or, you could have a glock, that isn't a "True" double action, and for whatever reason, the round doesn't fire. e.g. light primer strike. There is no 2nd strike capability. A revolver, you simply pull the trigger again. Unless the semi-auto is a "true" DA/SA or other external hammer such as a Sig P220 or 1911A1, you have to rack a new round into the chamber.
It's a moot point for me because I'd rack the slide to load a fresh round anyway. That's what effectively happens with double-action revolvers--the round that didn't fire is skipped rather than struck repeatedly. If you have a dud with a DA/SA semiauto, then you'd have to rack the slide after a couple of additional trigger pulls, obviously.
All guns are mechanical. All guns therefor can go FUBAR. I don't choose a revolver over a semi-auto for home/2am defense because of the "GUN FAILING". I choose a revolver over a semi-auto for home/2am defense because at 2am "MY BRAIN" may be what fails in responding properly.
That's what training is for--things like reloading and clearing malfunctions should be second-nature. I can only speak for myself, of course, but if I couldn't fully operate my semiauto under certain conditions--even to clear minor faults such as light primer strikes--then I wouldn't trust myself to fire a revolver at the right target, either, but that's just me. These are two views on the subject, at any rate, and everybody needs to decide for themselves what works for them.
I've trained in "Hot Houses" where you practice live fire in a building. There are audio shots being fired back some times. There's other noises made; etc... I've seen people forget to turn the safety off on some guns. I've seen people who forgot to load a round into the chamber.
That's what Glocks and M&Ps (et al.) are for--there's no manual safety to worry about and they're meant to be kept ready to fire at all times, with a round in the chamber, whether holstered or at the bedside.
That said, if anybody doubts the reliability of semiautos to the point where it bothers them, then by all means go with a revolver, which is a good choice, too (although I wouldn't trust a firearm of any type for defense unless I had tested it thoroughly first). For some perspective, however, remember that many would suggest a pump-action shotgun over any type of handgun, even though they're not any more reliable than a proven semiautomatic pistol--there's plenty of opportunity to "short-stroke" the action and occasionally they simply jam. Rifles can have similar issues, too. Every type of firearm has pros and cons for home defense.
I really haven't seen many light primer strikes at all, auto or revolver, when using quality self-defense ammo.
And when it does happen, it's most likely an ammo issue unless a particular handgun--of any type--has chronic light-strike issues (more common in revolvers, I believe, due to end shake issues), in which case it should be repaired before being used for home defense. I've never seen a problem myself with quality centerfire ammo, and it's pretty rare with quality rimfire ammo, as well. Also remember that squib loads can have exactly the same disastrous effect on revolvers if the barrel becomes obstructed, which should be all but unheard of with self-defense ammo from a reputable manufacturer.
But I've seen quite a few revolvers that have experienced cylinder lock-up for a variety of reason....it's not as rare as you seem to think.
For example, shooting some heavy loads at the range over several sessions could increase end shake just enough to cause the cylinder to bind at some random point in time if the gap is too tight on a particular gun. Those who are unfamiliar with such issues and don't monitor the tolerances of their revolvers--such as relative novices who were told that revolvers are ideal for them because they're totally dependable and cannot "jam"--could get a nasty surprise when their self-defense revolver does "jam" when they need it most. If and when it does--and I'm not saying that it's frequent, but it does happen--there's a decent chance that they won't be able to unjam it.
but that doesn't mean they aren't one of the most--if not THE most--robust, practical, yet affordable pistol designs in existence.
