I don’t think maps are a must for a reader, and I think it depends on the story as to whether the writer needs one. If the geography plays an important role in the story, a writer should definitely know where things are, and unless you’re a magician who can hold every detail in your brain without forgetting anything ever, a map could prove invaluable. As a reader, I’ve never really given a map a second glance, but also as reader I can tell if a writer isn’t really that clear on where everything is themselves. In some stories it can be very helpful; but if your readers are constantly having to go back to the map to orientate themselves it might be a symptom of a narrative issue rather than whether or not you’ve got a map available.
Since my current project is set for the most part in the same city, I’ve made a map of the city and its various quarters in relation to narrative landmarks (like the castle, where the MC’s living, basically any named locations where scenes take place) so that I’m not getting tied in knots when my characters are moving around. I do use it, too, and I’m very glad I made it. I also made one for the wider area. I think if there are lots of locations in a large-scale story that your characters may return to or refer to more than once, you should at least make a note of it. I’ve found that since I have three PoV characters running around the same city it’s also helpful for knowing where they are in relation to one another for Plot Reasons. If anything, it takes some of the stress out of writing character travel and makes sure that X enormous river or mountain pass doesn’t vanish mysteriously mid-story.
That said, I did not make one for my urban fantasy story, since it’s set in London and I had good ol’ google maps for that