I think you might be underestimating the breadth of front-end skills required to properly develop, test, deploy, deliver, monitor, analyze, and optimize front-end applications. Including the myriad third-party integrations that other teams need, from CS to marketing.
Well, I wouldn't have considered half of those things as part of "front end development" work, but it pretty much drives my point. I'm a firm believer in the idea that you'll be more effective at all of those things if you have a general baseline knowledge of CS, so that if you need to you can (relatively quickly) understand how and why all of your tools work the way they do.
