People saying that about the XBox said the same thing about the iPhone. They always say that when a company goes into a market that is deemed to be foreign for them. People had a different view of Microsoft IRT console gaming by the time the 360 rolled around.
The 360 was a success by default by virtue of Sony (and Nintendo) being almost a year behind Microsoft in releasing the PS3. For example, in the US the 360 was available almost a full year ahead of the Playstation 3.
For the 360 to fail, Microsoft would have had to kill it themselves. It was impossible with that big of a lead. It is very hard to catch up in the console market when you miss a launch like that.
* Phones are different, especially when it's a system used by various manufacturers. Just cause HTC released a crappy phone doesn't mean Samsung won't release an Awesome phone using the same base OS (as has happened quite a few times). You simply avoid the bad apples. Apple and WebOS were the only exceptions, and Blackberry to a lesser extent but RIM tends to OverSKU their product portfolio anyways to yes much lesser extent.
In addition to Microsoft releasing the 360 almost a year ahead of the PS3, the PS3 launched very near the Wii which is a cheap console - and they launched with outrageous prices.
1. So... Tons of people had already invested in the 360 already by then (console, Games, services, etc.)
3. The PS3 was ridiculously expensive, and launched late (and hence the 360 was already building a healthy title library).
3. The PS3 launched close to the Wii, at a ridiculous price range (reviewers almost unilaterally laughed at Sony for that) which was cheap by comparison and siphoned the low end console gamer market from under them.
The RROD issue was real, but it only slowed 360 growth. For a whole year Microsoft had little to no competition in the high end console market. It was impossible for the 360 to fail, literally. Anyone even predicting such a thing had no clue how the console market works.
A few comments:
1) IMO Sony's Playstation 3 launch wasn't hampered by the near-simultaneous launch of the Nintendo Wii, and the Wii's low cost wasn't the reason why it became more popular than the PS3 (and XBox 360 in the 2007-2009 time frame). The Wii became popular because of the motion controls, which drew in casual gamers. The Gamecube was cheaper than both the Playstation 2 and XBox in the previous generation but still was crushed by the PS2 sales-wise (and even outsold by the XBox in the U.S.).
2) I agree that the PS3's late launch hurt its sales. In video game console history, late-launching consoles almost always do not "win" their generation. The only exceptions to this are the Super Nintendo back in the 16-bit era (and that was a "sort-of" win for Nintendo - Sega had greater market share with the Genesis at the peak of the era in 1993-1994 and Nintendo went from having 90+% market share in the 8-bit era to around 50% market share in the 16-bit era) and the Wii in the current era (which had to do with its motion controls).
3) The XBox 360 was a success because it was a solid product, not because it was "a success by default". It was also a success because 1) the original XBox generally impressed people and captured a decent number of hardcore gamers; the positive opinions many people had of the XBox helped Microsoft build on that success with the XBox 360, and 2) Microsoft purposely launched the XBox 360 early (and discontinued the original XBox) so that it could boost its adoption rate. Launching early usually helps a video game console manufacturer but that's not always the case (see Sega Saturn, 1995).
4) I agree that the mobile computer OS market is functionally different than the video game console market. (Interestingly, there is one fairly high profile example of a video game OS creator following a paradigm similar to what we have with smartphones now - the 3DO back in the mid-1990s had a similar paradigm where the OS was purchased for use by hardware manufacturers. Both Panasonic and Goldstar (now known as LG) manufactured 3DO consoles. However, the 3DO bombed because the hardware cost was way too high for its time, and that hardware cost was high in large part because in the video game industry companies tend to make limited money on the hardware but lots of money on the software; however Panasonic and Goldstar weren't companies that created many video games.) Having said the above, I'm not sure the mobile computer OS market will be a carbon copy of the desktop/laptop computer OS market either, where an OS can now serve a user for nearly a decade and the next iteration of the OS builds upon the previous OS (i.e. backward compatibility). It is possible that Apple and/or Google (and all other mobile OS makers) will need to radically replace their mobile OS in a few years if they become bloated with backwards compatibility issues. Even if a radical replacement isn't needed, it is possible that items downloaded/purchased from their app stores now will at some point in the future not be compatible with later iterations of their operating system, which will require users to download/purchase similar apps again.
5) I personally think the whole "locked into an ecosystem" concern is overblown. How many times have we seen people, to use an example, own a Microsoft OS computer, use an Apple MP3 player (or smartphone), and browse the internet on their computer using a Google or Mozilla browser? This kind of thing happens all the time. In addition, how much money do people really spend for apps on their smartphones? Personally I'm someone who views purchasing apps when I can get free apps or free access via some other device as a waste of money, so I think I've purchased one app total (for Android OS) between all my different mobile OS devices, paying $5. (I'll add to that in the near future due to a $25 Windows Phone gift/rebate card and a $15 iTunes gift card, but even those expenditures won't be on my dime.) Even if people do purchase apps, I'd guess they are spending a fairly small amount of money total for those apps (say, less than $100 or even less than $50), an amount that is considerably less than what many people spend/have spent to buy new video games for a new, more powerful console. The much bigger "locked into an ecosystem" issues as I see it are 1) most people are afraid to learn a new mobile OS and how it works and 2) whether developers support a particular ecosystem (i.e. develop apps for it). With the former factor, the simpler a mobile OS is to use, the less that issue comes into play.