Technology is incredibly complex and, at the same time, incredibly unreliable. As a result, we build backup measures into the DNA of everything around us. Our laptops switch to battery when the power goes out. Our cellphones switch to cellular data when they lose connection to WiFi.
At the heart of this resilience, technology is constantly choosing between the available providers of a resource with the idea that if one provider becomes unavailable, another provider will take its place to give you what you want.
When the consumers are tightly coupled with the providers, for example, a laptop consuming power at Layer 1 or a server consuming LAN connectivity at Layer 2, the choices are limited and the objective, when choosing a provider, is primarily one of availability.
Multiple providers for more than availability.
As multi-provider solutions make their way up the stack, however, additional data and time to make decisions enable choosing a provider based on other objectives like performance.