Because I said so myself, let me answer your question:
No, you do not have to.
If you look at the answer you linked to or at mine above, you see that they suggest techniques which aren't easy to follow on screen. Both answers suggest to mark your printed text using pens one way or another.
Printing out, grabbing pens, start marking is one thing: easy. If you want to do that on screen, you need special tools (maybe built in to your word processor, maybe not). It's more tedious in most cases.
But there are special tools for doing this. Most of the markings I describe in my answer are available in the word processor "Papyrus Autor". The creator of that marking technique (Eschbach) worked together with the Papyrus team, so you do not have to print it out anymore (if you buy "Papyrus Autor" and you write in German).
So if you do not want to use these techniques or you have a way doing it on-screen, you do not need to print them. Only if you want to get a new perspective.
That's another reason, why printing out is suggested. You have a different look on your story. But to get a new perspective, you also can reformat it and read it on-screen. Instead of Courier 12pt, use Times 8pt, 50 lines instead of 30 a page or whatever.
New perspectives improve revising, because your text is placed on a spot where you do not expect it. Just moving the paragraph from the beginning of a page to the end, can show you what's wrong with it, because your mind has to rethink.