If other peoples work is reliant on yours then you should know how their part of the system transforms your inputs

Similarly you should fully understand how all the inputs to your part of the system are generated

No matter your coupling pattern, if you have more than 1 person product, knowing at least one level above and below your stack is a baseline expectation

This is true with personnel leadership too, I should be able to troubleshoot one level above and below me to some level of capacity.