So... the article... Hypothesizing that it's primarily due to tight tolerances. Shows that they're indeed tight, and have remained similar to legos made 40 years ago. However, similar to what appear to be "random cheap dollar store building blocks." Best sentence "Honestly, I don’t know much about plastic manufacturing – but the LEGO blocks appear to be created from harder plastic." - This is why they made interviews. Really wasn't so interesting and didn't answer the question.
Lego is ABS which is relitively expensive while most competing bricks are made from polystyrene.
The tolerence is the key thing though - we've got a reasonable selection of lego here as well as a few sets of Mega Blocks, Kreo and the odd chinese brand, and there's a huge difference in fit between brands with none coming close to Lego. Try watching your kid build something only to be unable to play with it because it keeps falling apart because the brick fit is sloppy
