Comment by robmccoll

Yes! You are best served by learning what a tool is doing for you by doing it yourself or carefully studying what it uses and obfuscates from you before using the tool. You don't need to construct an entire functioning processor in an HDL, but understanding the basics of digital logic and computer architecture matters if you're EE/CompE. You don't have to write an OS in asm, but understanding assembly and how it gets translated into binary and understanding the basics of resource management, IPC, file systems, etc. is essential if you will ever work in something lower level. If you're a CS major, algorithms and data structures are essential. If you're just learning front end development on your own or in a boot camp, you need to learn HTML and the DOM, events, how CSS works, and some of the core concepts of JS, not just React. You'll be better for it when the tools fail you or a new tool comes along.