Yocto Linux can be stripped down to the bare minimum for embedded applications. You can reduce your attack surface by a lot. The advantage of Linux on embedded is your new developers are up and running immediately. Something not possible with all the rest of os/rtos. Additionally lots of packages for diagnostic utilities like iperf etc are available even for obscure processors that run Linux. As long as battery life isn't a concern, let embedded Linux be an overkill, the advantages are just too great.