As far as the marketplace goes, sure. But Linux would be a lot more stable if it had used Andy's ideas. Slower, sure, but more stable. As we've seen with Microsoft, stability tends to be low on the list of desirables.
You use that word, but I do not think you know what it means.
I had my first 1 year uptime on a Linux server around 1996. My Linux desktop at work has never crashed in the 3+ years I've been using it. I haven't had a non-test box Linux machine crash in over a decade (I was employed as a kernel developer for a year in 2002/2003 and that doesn't count - I was working on crash dump code so I had to make the machine crash). Not even my Macs are that stable.
Tanenbaum is bright guy, no doubt about it. It's just that he is dead wrong about OS architecture. I think he may be a bit jealous too, because Linus is smarter. I've followed lkml since 1995 and I'm a bit jealous of Linus' skills, to tell you the truth.