Every element serves multiple functions. Every function is supported by multiple elements. Like trees in a forest who lean on each other for support in heavy winds, systems that are integrated are stronger and less likely to fail.
In a linear chain where each link is connected only to its immediate neighbors, the strength is determined by the weakest link. On the contrary, in a highly connected network like a spiders web, where every thread is connected to many others, any individual thread can snap and the web as a whole will remain intact.