Well that's actually Berzerker's opinion -the quotation of the translation stops at the paragraph above. If you were asking me, I would say that the certification track that one will follow will be defined by the demands of his current employer or by his expectations-ambitions. In example, one could choose to specialize on the design of complex networking structures, which is importand for ISP corporations. His job would possibly involve the design of the whole network, the choise of critical importance equipment, some tough decisions about the way the various data will be handled through the network, monitoring the traffic statistics and evolving the network continuously in a way that everything keeps up with the current demands. One other would specialize in setting up and monitoring the firewalls, Intrusion Detection systems etc. Others would specialize in maintaining and optimizing various services according to the current demands. All these require different kind of experience, for example the security guy would not need to know how to design efficiently the whole network, while the designing guy would not need to know the technical detals of the VoIP network implementation for the corporation's demands -that's the job of the third guy. Of course in smaller corporations the demands would be different, they would probably require persons with all arround knowledge, but even in this case some specialization would be necessary at some point, as the network grew and expanded.
Still, the certification track will not necessarily define what one has specialized and is skilled in. His working experience will define this better. I believe that any skilled networking professional can easily specialize in any networking area at any point, and start building experience there. It's just that there is not enough time to keep up with everything in a working enviroment, not that the different specializations are incompatible with each other.
