The Arduino is also much simpler, and you control all the software that runs on it, whereas in Linux there is probably 1000 times as much software running, almost all of which is code from elsewhere.
Now most of that code is pretty good (the kernel), but because there is so much of it, you cannot be absolutely sure. With something as simple as an Arduino running all your own code, you can be sure (or as sure as your testing allows), that it will do what you want, in the timescales you want.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed. Here's an example...
"My grief counseller just died, luckily, he was so good, I didn't care."