As far as the original article itself,... a 90% hit rate is a good thing, how?
People say "bell curve" like it's magic. First of all, bell curves come in all sorts of steepness. Second of all, the bell curve lives within d20.
Using a 3d6 instead of a d20 does NOT institute a bell curve. Whatever the number if you need to hit, you either make it, or you don't. Whether you use a 3d6 or a d20, your chance of success is a single fraction. All systems involving target numbers are equivalent to a percentage chance of success.
What 3d6 does, however, is to steepen the curve. If you have a +10 to hit and you need a total of 20, both are roughly equivalent. If you suffer a -2 penalty to hit, with a d20 you lose 10% of your chance to hit. With the 3d6, you lose more. Those small variations, close to the averate go hit bonus, are the most common variations in 4e. In other words, using 3d6 may overall make characters more accurage, simply because the target number now rests under the bell curve, but it actually accentuates differences in to-hit between PCs, in a certain sense, restoring the fighter-wizard disparity found in 3e. Instead of martial-magic disparity, however, you see optimized-unoptimized disparity, and single-attribute vs. MAD disparity.