After 40+ years as in electronic, software developer, OS and App, Networking, SysAdmin, DBA and DevOps I see it all as a multi discipline. Knowledge in Electronics, CPU design, Compiler development, OS design, communications, Business management and user interfaces all relate and a "Rock Star" would need to be an expert in them all.

Most Dev's stop with App dev and business design. Some go on to UI or compiler performance. System a little and communications and electronics almost never.