Kevin Guthrie has been a nonprofit leader for more than 30 years. But when he describes the strategic evolution of his organization, JSTOR — which specializes in academic archiving — he sounds almost like a Silicon Valley CEO.Take JSTOR’s first $700,000 in seed money, which came from the Andrew Mellon Foundation in 1994. That resembled a venture capitalist’s early support, Guthrie says. Other foundations, such as Sloan, Howard Hughes, and MacArthur, pitched in later, too. Or consider the nonprof...