"creation of acidic water vapor from the dissolved nitrogen and sulfur oxides which corrode the delicate system components"
I guess stainless steel isn't what it used to be.
Delicate system components is not the boiler heat exchanger. they are referring to electronics. But you got to have a leak somewhere before the vapors get around to the outside of the boiler where the wiring is. everything on a condensing boiler is stainless, plastic, or rubber...or should be. If you got vapors drifting off your boiler, something is terribly screwed up, and yes those vapors will destroy electronics over time.
No, it isn't. They have alloys now that are far more corrosion resistant than earlier versions like 300 series steel. A good design and corrosion or heat isn't a factor but that design has to be good across the board. They obviously have a weak link.