What is so unreasonable, illogical, and extreme about it ?
The US economy is the not the same as it was 200 years ago, or even 50 years ago. It's much stronger and healthier - due to globalization. Therefore, the economy must grow more than it's historical averages. Also, increased participation in the stock market throughout classes, and other things like the development of 3rd world countries (which gives the US more opportunity to expand it's markets) causes the US economy to be that much stronger. Historical averages are exactly how they sound, "historical."
If the US economy fell to it's knees(something much worst than a depression), would you expect the same historical results? No. Then why would you expect them if the opposite happened?