The more equality, the more the economy is built around consumer consumption instead of investment, as the savings that are used for investment come mostly from the class that saves the most of their income (ie, the wealthy). And consumption is a much more reliable engine for an economy than investment; investment is made based on inherently unknowable future prospects, so it is vulnerable to herd-style decision making and violent swings between bubbles and crashes (something that anyone following the past four years would know already). While consumer behavior during a recession can be self-defeating (people want to save during a recession, but that will just destroy sales and take income with it), consumers in general make much more rational and predictable decisions. They're never the ones who cause the crashes. It's simple.
