Really enjoyable article, though that may be because I love the L4D franchise and am sort of a achievement whore.
When i got my first game on Steam and saw the achievements, i HAD to get them all. It might take me time, but i WILL get them all (though i do have some worries about TF2. Jesus, over 300 achievements. Fun
!).
When me and 3 of my friends decided to start trying out expert, we at first used tricks to finish them (for example, in L4D2, the Dark Carnival finale, if you jump to the right place and crouch, no zombies will spawn when the finale crescendo event is on). The difficulty jump from advanced to expert is REALLY big, it was amazing how fast anything could take you down. So we had to make it a bit easier.
But after playing a while, we decided to play it normally. And it's actually fun. Much harder, but the feeling was pretty damn awesome. But still, i know it's fun to do what the article-writer did.