Only if they wrote why in it though, plenty of people (unfortunately myself included) fail or forget to add meaningful comments or they let their comments go stale when making changes by forgetting to update them (I do it a lot too), and some people also use horrible function names that don't make any sense.

So it only really applies to source code intended to be released where care was made to ensure it would be readable, it might not apply for source code never intended to be public, such as stolen, leaked, or posthumously released. In this case the only real benefit is that it can be recompiled on different architectures provided there isn't a dependency issue preventing that.