I think the point Allan was making in the article is that the EGR system needs to be serviced regularly (every 40-60,000 km????). This could be a chemical clean such as the walnut shell treatment, EGR cleaner or taking the manifold off and manually cleaning. This becomes another service cost that I think most people wouldn't want to pay on a regular basis and are not aware off when buying a modern diesel.

As AGman said if you take away the soot, oil mist or both then the problem does not occur. The engine emissions however are not as clean