Same reason there's a thriving market of other editors really, horses for courses. People use best what they use most, sometimes they make a conscious decision

Same reason there's a thriving market of other editors really, horses for courses. People use best what they use most, sometimes they make a conscious decision about it and sometimes they just fall into it. I imagine that a lot of tools are just used without much questioning, and that's fine. The basic feature sets of text editors are pretty much the same. Write, delete, move, copy, paste, save, create. The main benefit is about choice, I keep a stack of text editors around just out of curiosity, because I like playing with software and editors and sometimes you find features you think are neat, and then go off to try and replicate them in your main editor or tool. Open source software is good at communicating ideas and text editors as a whole have really improved each other over the last three or four decades.