O.K. fine, I'll take your word for it that Subaru sells non-AWD vehicles somewhere in the world, just not in the U.S. or Japan. But for all practical purposes, the fellow in question lives in the U.S. so every Subaru he will find will be AWD.
My statement that Subaru's AWD systems are durable is not to suggest that they'll never break. It also doesn't imply that therefore every other AWD system is unreliable.
While this discussion started at as an Audi Quattro topic, it devolved into a discussion on Audi's in general, not the quattro system. It then devolved into mentions of Volvo, VW, and Subaru.
The comment about MB's 4-matic system was just a freebie. No charge to the reader.
Last, I'm afraid I'm not quite sure what you mean by "...to describe quattro as reliable is to suggest it can go wrong. Put simply, it doesn't, and won't." When people suggest that something is reliable, it doesn't mean that it will never break.
I really don't have any personal experience with Audi Quattro's and have never spoken to anyone who has owned one. The reputation that they have is that the system is highly regarded and is quite reliable (no implication that it will last forever without breaking).
Have a great day.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".