Understanding the idea behind setting request auto if only limit is specified

Hi,
When reading in the documents the section on "Managing Resources for Containers

There is this Note:

If a Container specifies its own memory limit, but does not specify a memory request, Kubernetes automatically assigns a memory request that matches the limit. Similarly, if a Container specifies its own CPU limit, but does not specify a CPU request, Kubernetes automatically assigns a CPU request that matches the limit.

I don’t understand the logic behind it, why automatically set a pod request to the same number as the limit if only a limit is specified? doesn’t it take to much from the node? and doesn’t it mean that when the pod reaches its request limit it will also be restarted by kubelet since it also reached it limit?

Thanks in advance
Oren