That there is a field called Innovation Economics basically proves my point. As it states in the linked it is fact quite different from standard economic theory.

You state in another post that English is your second language. When you say 'textbook definition' you are implying canonical usage, not there exists a textbook that I use that defines this.

>None of the textbooks in economics (HS and undergraduate courses) or economists I have read assume this to be true, or even a useful approximation for most markets.

That is really striking. You have never taken microeconomics? Never dealt with the efficient market hypothesis? Ever taken a economic theory class? This is possible since European approaches to economic education differ quite a bit from American ones. But it is extraordinarily difficult to have mathematical models of markets where participants have informational asymmetries.

>Of course they are, for example in every study ever written on globalization, the structure of corporations, corporate governance or insider trading. Or is there some special definition of the terms you're using?

These things are not economics per se. They are interesting things to study, and yes they involve networks. But just because they exist does not mean they are subjects in standard economic textbooks.