That is simply not the case. The XP operating system is based on the Windows NT 5.0 kernel that was developed in the late 1990’s. In fact, if you do a VER command on Windows XP it lists the version as 5.1. That is NT 5.1.
While NT 4.0 was the last of that name, originally, Windows 2000, the immediate predecessor of Windows XP, was to be called Windows NT 5.0, but Bill Gates had the name changed to better sell the Y2K fixes in Windows 2000.
The bottom line is that the 5 kernel is VERY old in the Tech world scheme of things, and every exploit that has gotten a patch over the years makes the kernel unwieldy and extremely difficult to patch any longer. From a security standpoint, it really has reached the end of its life. Every exploit from this point onward costs a great deal to remedy, and the codes is very difficult to maintain, and Microsoft has reached the cost of diminishing returns on the ability to patch XP. That’s it. End of life.
Don’t blame Microsoft. Blame the attackers for continuing a war and they are always on the lookout for new exploits. Nothing made by man is unbreakable by man. You wouldn’t expect a cavalry charge with soldiers on horseback to defeat a tank army, would you? How can you expect a 14 year old operating system to be able to survive 14 years of learning the code and exploiting it that the hacker community has now had? When do you decide that that system is no longer reasonably defendable? Microsoft as a sue-able corporate entity has to take into consideration that if an exploit can destroy or compromise someone’s data or financial information they could wind up in court being sued for allowing XP to continue. And believe me, Microsoft sees frivolous and BS lawsuits all the time from greedy lawyers hoping to scavenge some ready cash form tech ignorant juries and judges. Microsoft realized this when they set about creating the 6 Kernel (Vista/Windows Server 2008/Windows 7/Windows 8/Windows Server 2012) and they actually are hard at work on the series 7 kernel. I expect folks to be pissed at Microsoft when THAT is released, but it is required in this ending war.