Foundational knowledge can be pretty far upstream of functional knowledge.

Whether you can't describe the analog circuits that correspond to the opcodes of the major mobile architectures running the platform of the app you're designing a UI for, or you couldn't have built any of the services you're hosting on from scratch, no one is going to be disappointed.

There are more people making more money off whatever we're currently calling making computers do things than ever before in history. The rest is largely business as usual.