With the amount of patching we do for both Linux and Windows they both always have a few screws loose.
You see, you're looking at it wrong. You seem to think patching a flaw = good security. That's not true. Let me give you an elementary example:
1) You build a house out of straw.
2) I build a house out of brick
3) A hurricane whips by and hits both of our houses.
4) All of your straw gets blown away.
5) Only one brick on my house comes loose.
6) You patch your house so that the house lasts a few minutes longer under strong winds (it's made out of straw after all).
7) I only need to patch up that one brick by making the cement more adhesive.
This is the difference between Windows and Linux. Windows is the house made of straw and Linux is the house made of brick.