Why?

In the current context talk about a recession isn't due to any sort of tech bubble. Talk about a recession is due to issues with the financial system and debt.

A small recession caused by a tech bubble would honestly be more desirable (in my mind anyway) than what issues with the financial system and debt could produce.

Also, a downturn in the tech industry now wouldn't necessarily be because of a tech bubble, but rather due to lack of confidence in the financial system as a whole.

Actually, they're connected: the Fed is trying to encourage a recovery in the general economy with low interest rates/quantitative easing, which has the effect of creating asset bubbles in some sectors (tech, commodities, ...) as investors look for decent returns.

The two are not mutually exclusive. There is a recession for lower and middle-class jobs, and a tech bubble.

Why does it matter? The point of the essay is that if you're going to start a startup, it shouldn't matter what the current economic conditions are. You and your idea will either succeed, or they won't. It has much more to do with you and your idea than with the economy.