Good example!
Similar analogies could be made about physical security.
A householder gets new locks for his doors and neglects to notice there is a small window the attic. A small burglar could get in through the small window.
That does not mike the house a bad house. It just was not made to be a fortress.
The 'flaws' in the design of any CPU might be necessary to get the level pf performance that users expect. As this time that has not been proven to be true or false.
Right now, the really big threat is so many users are not vigilant about computer security and allow too many unsafe things to get into a personal computer.
I found a link that claims you do not need an AV programs anymore.
No, I am not going to put the link here.