No, I don't think I agree. There are many terms that are not relevant to modern life but can be found in the dictionary although admittedly they were probably in use for more than five years. But the significance of the phenomenon (or whatever) to which the word referred must also play a part in the decision as to whether to store it up for posterity. The 'dotcom' fiasco probably falls into the same category as the 'South Sea Bubble'; that stock market crash dates back to 1720 and is still taught in History lessons. I suspect that in the future the 'dotcom' crash may also be taught.

For some stuff on the SSB see:

http://www.dal.ca/~dmcneil/sketch.html