An interesting point is that about half the companies we work with want their front-end developers to show full-stack understanding and strong CS (the argument is usually that they want to hold the entire team to the same standard so that people can move around freely on the between teams). The other half of the companies don’t care about anything other than productive, practical front-end coding (often focusing on speed). We find that front-end interviews value speed a lot.
Full-stack engineering is like having a veterinarian operating human beings rather than a surgeon or viceversa. Domain knowledge specialization exists for a reason.