Using quantitative finance is just a part of investing

Computer science is no more about computers than astronomy is about telescopes
Edsger Dijkstra

In spite of all of the advancements in quantitative tools and the use of computers and large databases, effective investment management is not about technique but rather about the process of meeting financial goals. Since some of the risks faced by investors are not quantifiable, a focus just on tools and numbers is insufficient to gain success. 

The advancements of finance have been able to better formulate the investment problems, but does not always provide solutions. We have a better understanding of factors and can better decompose alpha and beta, but we are no better at predicting what will happen to factors such as growth and inflation over time. There is still significant room for  theory, testing, and analysis - the science of investment management.