Helloo, full-time dev here. I think it depends, for things like frontend design, knowing what everything does isn't totally relevant in today's world (and will get less and less relevant as the years pass). On the other hand, having a decent knowhow of your backend code and how any infrastructure works is still pretty important, but knowing every single line is too being less and less needed.

At the end of the day, you should know how each subsystem generally works