WordStar is popular with science fiction writers for more fundamental reasons. (Not because it doesn't have spell check or isn't connected to the internet.)

Wordstar treats the text like a long-hand manuscript. You can add notes to yourself like "fix this!" and deal with the edits later. Or, you can block copy large sections of text and have the computer keep a reference to it without having to "copy and paste" it immediately. I've seen George RR Martin write that he likes how easy it is to move large sections of text around in WordStar.

Here's how the SF writer Robert J. Sawyer describes it:

"... as a creative writer, I am convinced that the long-hand page is the better metaphor.

Consider: On a long-hand page, you can jump back and forth in your document with ease. You can put in bookmarks, either actual paper ones, or just fingers slipped into the middle of the manuscript stack. You can annotate the manuscript for yourself with comments like "Fix this!" or "Don't forget to check these facts" without there being any possibility of you missing them when you next work on the document. And you can mark a block, either by circling it with your pen, or by physically cutting it out, without necessarily having to do anything with it right away. The entire document is your workspace...

WordStar's ^Q (Quick cursor movement) and ^K (block) commands give me more of what I used to have when I wrote in longhand than any other product does. WordStar's powerful suite of cursor commands lets me fly all over my manuscript, without ever getting lost. That's because WordStar is constantly keeping track of where I've been and where I'm likely to want to go. ^QB will take me to the beginning of the marked block; ^QK will take me to the end; ^QV will take me to where the marked block was moved from; ^QP will take me to my previous cursor position. And, just as I used to juggle up to ten fingers inserted into various places in my paper manuscript, WordStar provides me with ten bookmarks, set with ^K0 through ^K9, and ten commands to jump to them, ^Q0 to ^Q9...

WordStar, with its long-hand-page metaphor, says, hey, do whatever you want whenever you want to. This is a good spot to mark the beginning of a block? Fine. What would you like to do next? Deal with the block? Continue writing? Use the thesaurus?

After another half hour of writing, I can say, ah hah!, this is where I want to end that block. And two hours later I can say, and this is where that block should go. I'm in control, not the program. That's clearly more powerful, more intuitive, and more flexible than any other method of text manipulation I've yet seen implemented in a word processor. That WordStar lets me have separate marked blocks in each of its editing windows multiplies that power substantially: imagine doing a cut and paste job between two versions of a paper document, but being told that you could only have one piece cut out at a time. Madness! Yet that's what WordPerfect, Microsoft Word, and others would force you to do. (In WordStar 7.0, you can even, in essence, have two marked blocks per window, toggling between them with the "mark previous block" command, ^KU.)"

http://sfwriter.com/wordstar.htm