IME : they had to move up the stack, in order to access better employment opportunities.
I'm trying to implement these sorts of changes (and many others) right now at my own place, but it's quite frustrating from the other side too.
1. Being paid much less than my similarly leveled colleagues
2. Needing to work with engineers well outside my timezone
3. Being hounded by recruiters to do bluetooth comms and nothing but bluetooth comms
4. Having to be very careful to not put myself in a position where I need to fly to China to deal with manufacturing issues on a moments notice
5. Lack of remote work opportunites for obvious reasons
I do enjoy working on low level code but not enough to deal with the industry in its current state.