Because his fancy Denon pre-pro bit it and Denon/Marantz (same company for a while now) couldn't fix it.
, he was quite the Denon fan before that; he's been a Yamaha fan since getting a Yamaha pre-pro and now repeats info mcode has been providing for a while about reliability stats reported by part of the industry; the stats aren't conclusive IMO, even those provided by an insider like mcode (who works for an unnamed and mysterious installer that pitches in on design/consulting work with various consumer audio gear).
Also note he is specifying Sony's ES line, their upper end line. Sony kind of went their own way for room eq and volume calibration, which some people knocked them for as it wasn't perceived as being very good, and Sony was having some focus issues for a while when they fell from grace somewhat due to bonehead corporate expansion in general. One of my more durable avrs has been an inexpensive Sony, but it lacks some of the bells and whistles, too (like hdmi). I've got a couple of Denons that have been just fine; also have an Onkyo and have had the famous hdmi/network board issues with the Onkyo (fixed by Onkyo) as well as a failed Pioneer (and Onkyo/Pioneer are now combined as far as such products go). Yamaha does likely retain the lead in reliability, and hasn't changed hands or used contracted production facilities; others haven't had as deep pockets from a stable parent organization to help out, and Yamaha does actually go thru hdmi certification whereas others don't. That said, I've never had (nor really wanted) a Yamaha.
That's my take at least.
