Exactly. Also why isn't Apple advertising the fact that millions are still using Windows XP which came out 10 years ago? Maybe this whole fragmentation issue is really meaningless?
A few reasons:
1. Windows XP is still getting security updates by Microsoft, so if you want to use onlinebanking with Windows XP, you can do so without fear.
BUT this will change next year, because Windows XP will only get security fixes until April 2014 and from that point on, it will become increasingly more dangerous to use Windows XP for stuff like onlinebanking, shopping and everything else that has to do with financial and private data.
Android Gingerbread has already reached this point, the last update for Android 2.3 was in September of 2011.
If there are any security holes in Gingerbread, everybody will be able to exploit them and they will never be closed by Google.
2. Windows XP as a desktop system is less dependant on new system-wide APIs for new features than mobile OSes.
People don't expect to have the ability to share everything on their computer directly to Facebook, so they don't need a system-wide API for that.
If they want to use maps, they just go to Google Maps instead of loading a program which displays maps, so no need for a Maps-API.
Desktop operating systems have more abilities than mobile OS and people also don't expect more features directly integrated in the OS from them, like they do with iOS and Android.
People are also often ignorant about the possibilities of newer operating systems or newer hardware, so they reject upgrading, even though they would probably love some features Windows 7 (or maybe even Win8) has.
But: There are many things Windows XP can't do and all those who need those features will already know about this kind of fragmentation.
Modern games? Won't run on Windows XP, because it doesn't support DirectX 10 or 11.
IIRC there's also no support for Office 2010 and 2013, so if you want to use those as a user - get something newer.
But this whole fragmentation stuff has two implications:
Customers are using an OS that is less secure than possible for tasks like banking and soon also NFC payment.
Developers can only target a small number of users with advanced features that require support of newer APIs.
For Windows XP, the second part is less important nowadays, because the most important API that isn't supported on XP is DirectX 10/11 - and developers just target consoles instead of PCs now.
And that is also happening with Android:
Developers target the platform that is more specialized for the task of "X" and that also has more people who actually pay for stuff (see piracy on PCs and piracy and "I just use the free one with ads instead" on Android) - the iPhone.
About users using the latest browsers on Android 2.3 Gingerbread:
Nope!
Chrome for Android requires Android 4.0 Ice Cream Sandwich and it is much improved over the generic "Browser" of earlier Android versions.