Are you proposing compiling on the target? For a vast number of embedded systems that is not only impossible (insufficient disk and memory) but also incredibly slow.
At the end of the day you need some cross compilation just for board bring up.
If you're playing with some platform for which this has already been done, then sure, but that's not really the "normal" way of doing embedded.
Embedded just means ARM 99% of the time and it's cheaper and easier to use native ARM servers (AWS has them cheap) than to make 100% of software cross compile. Some parts of the firmware might need to be cross compiled but those projects are designed to cross compile.