It depends a lot on circumstances. Most developers today building mobile apps, web front-ends/apps, or even working on the backend simply do not need foundatio

It depends a lot on circumstances. Most developers today building mobile apps, web front-ends/apps, or even working on the backend simply do not need foundational CS knowledge, though I suggest it would be better in most cases, and more often than not a 'positive signal' of general capabilities. In my own experience, I started out working on embedded, designing software for fairly complex networking gear - and we were even making our own ASICS. Then moved on to a variety of other thing and I'm pretty sure I've literally never seen a sorting algorithm implemented, let along having done one myself. I've even tried to find excuses to do one, but always fell back on deference towards more established libs. My own CS background has been helpful, but more in the general sense, and I'm certain that someone with enough self discipline could have very well accomplished the same. Specifically, none of the most applicable basic skills (i.e. language mastery, API familiarity), best practices, or even more architectural issue (i.e. tech selection), or planning approaches were derived from my CS background. CS is a 'good indicator' and generally preferred but surprisingly not directly applicable in most scenarios. Obviously, in many cases it is.