Yes, because at the time there were only four or five main junctions for cross-country internet peering locations. Seattle was not on that list and if you are not going to be local then why go to CA and compete for space, data-center engineers, and peering with every other late-90s dot-com on the planet when you could go to an area with equivalent infrastructure and less competition for the resources. The reason so much telecom infrastructure terminated in that region was due to proximity to the government center of gravity, but also due to simple geography and the tendency of new telecom infra to be built out in parallel to existing telecom infra.

Oh, you were trying to make some sort of sinister innuendo based upon your complete lack of understanding of the telecom industry in the original dot-com era and the existing long-haul infrastructure at the time? Ok.