I think it's okay to copy and paste from a tutorial if you know what's happening and how to build it on your own! An example:
Learning node.js you'll often have this first step of creating a server.js. Maybe this is your fourth "Let's build XYZ with Node.js" tutorial and you already understand all the bits of that code and why everything where it is. So now it's absolutely okay to copy and paste.
But if you think omg what's going on there?! Learn the basics. You won't get anything from that tutorial if you just copy and paste.
I think the biggest problem with that tutorials is that people with just a minimal knowledge of javascript really think they'll understand Node.js with one or tutorials on how to build a Todo App.
At first you should know what does a server do? How and why they respond the way they do? What are the key things in Express and why is everybody using it?
And after you got this basics in your head: it doesn't matter that much how the code exactly looks – so go on and copy that stuff.
Matti
UI Designer & Webdeveloper