We create our world and our studies of it from the base of our assumptions about it.
Transnationally monopolistic variants of capitalism, which is what you seem to be refering to as "economics", exists but that is hardly to say that it works, especially the evidence of how it is hollowing out our country.
Mixes of tightly-controlled free-market and government-centralization of basic necessities have worked all over the place and certainly are also "economics". Hell, Soviet communism "worked" for a lot longer than the current yee-haw cowboy unbridled Wal-Mart scorched-Earth form of free-market theory as "worked"... and they're all three "economics".
The market does not regulate itself, if that's what we're talking about. The market creates competition for a little while until someone falls into a natural advantage which is quickly pressed into monopoly through the pressure wealth can put upon government and law and then...
There are no more market forces, there is just the survivor of long-past market forces that mutated into a force large enough to game the system toward itself. Game the system into allowing daytrading and predatory lending and all sorts of shadiness because more money can be made in the short term.
And it all eventually cascades into Big Troubles.
Yes, that is as it has happened, sure. But largely because the economic forces that got so large bought out those who would regulate it and went into a short-sighted greed-spiral.
If we start from the idea that whatever happens is what works and that whatever happens is right, sure, that is exactly economics, I suppose.
But I am inclined to choose a different path.