The very article mentions at the bottom that AMD has its fair share of nasty bugs recently, too. If anything, I would expect AMD to spend even less effort on validation (because they are not flush with cash).
Remember, a lot of the Zen arch was developed by Jim Keller, who is the brains behind the Athlon 64.
Although AMD’s response in the forum was that these were isolated issues, phoronix was able to
reproduce crashes by running a stress test that consists of compiling a number of open source
programs. They report they were able to get 53 segfaults with one hour of attempted compilation.