Even though people are right about the license being a reason one has to keep in mind that there actually is quite a few other BSD licensed (often real time) op

Even though people are right about the license being a reason one has to keep in mind that there actually is quite a few other BSD licensed (often real time) operating systems targeting embedded devices, like Contiki, Minix, TinyOS and others. I think the community and quality of documentation as well as not being controlled by single entities are a big part. It's not just the license. There are quite a few ways to get around using Linux in many use cases without caring about its license. And there is Toybox.