Windows was designed to run on white box PCs. It wasn't up to the PC manufacturer to ensure that Windows ran properly on each different model of their PC.
If I have an HTC phone I have to wait for HTC to prepare the latest Android upgrades, I can't just upgrade it myself.
Fragmentation on Windows wasn't a problem because if you hadn't upgraded to the latest version of Windows it was because you didn't run anything that required it.
If you haven't upgraded to the latest version of Android it's because you can't.
You are talking about a different issue (the OS having to support different hardware platforms).
I was talking about developers claiming fragmentation makes it hard to write programs for the OS running on different hardware platforms. My point is that the same level of complexity is involved in writing an Android app running on multiple Android versions and mobiles, and in writing a Windows app running on different Windows versions and PCs. And in both cases, it can be done relatively easily.
If I have an HTC phone I have to wait for HTC to prepare the latest Android upgrades, I can't just upgrade it myself.
Fragmentation on Windows wasn't a problem because if you hadn't upgraded to the latest version of Windows it was because you didn't run anything that required it.
If you haven't upgraded to the latest version of Android it's because you can't.