Adler believed that each idea would bring you face to face with the questions and issues that human beings have been wrestling with for centuries. He believed that studying them would yield important connections between the ideas. Further, he believed that many seemingly "intractable problems" might find surprising help from other disciplines.
Because of the advances in human knowledge, many of the disciplines have become siloed and cut off from each other. This kind of "methodological reductionism" is often a great strategy. It leads to breakthroughs because people are focusing all their time and energy on specific problems in their area of expertise. But very often, you run up against problems that are not as easy to solve. In those cases, the lack of breadth is a liability.
Imagine that you and your team of computer scientists are digging down to find a reservoir of discovery, and you've been digging down and down inside your little silo of expertise. But you just can't find the breakthrough. You can't find the reservoir. Then imagine that your colleagues in the next discipline (let's say psychology) have been digging down in their silo as well, and they've reached that reservoir already but from a different angle.
Adler believed that deeply understanding these ideas would help those two groups help each other and exponentially increase the potential for human knowledge to increase.