I'm not a huge fan of the whole full stack developer non-sense, but I am starting to see why it's in demand. For most things, you need a working knowledge of both.
Serverless of course closes the gap from the back-end further for us front-end developers. Exciting time to be witnessing this shift!
Perhaps what we do need to do is dispel the notion that a full-stack dev is great at both the front-end and the back-end. A healthy way to look at it would be to think of a full stack dev as understands one, masters other.
Both subjects have such a wide berth of knowledge. You're going to take time to truly get to a point where you're making good, long-term decisions on both sides of the half.