Debian is all over the place in embedded. It's pretty much the de-facto distribution (you see Yocto, Arch, Ubuntu server etc too) for consumer boards. Not sure what the distribution is in private industry, but typically manufacturers provide Debian images at a minimum. This is a problem for embedded systems because you're relying on a company to provide hardware-specific patches. While those are typically kernel patches (and so somewhat distro-agnostic), most people don't want the hassle of compiling their own kernel. That means you're likely going to be using Debian.
It's not, although I would admit that it's painful to learn. I spent my fair share of time learning it, and can now understand what's wrong with my configs in a split second when it doesn't work. Overall it's faster and easier to search with than apt, from my (very small, I admit) experience with apt. The dependancy system works really well, even when messing around with upgrades/downgrades/uninstalls too.
And I admit that a few years ago I would rank apt as much better than yum. Matter of preference / habit I guess.