Many photographers regard prime lenses as superior to zooms, since they often offer better image quality and more creative versatility via their wider apertures. Nonetheless, when it comes to landscape photography, sometimes, the balance of requirements is a bit different. This excellent video features an experienced professional discussing why zoom lenses are the better choice for most landscape photographers.
Coming to you from Mads Peter Iversen, this great video tutorial discusses why zoom lenses are right for most landscape photographers. I generally agree with Iversen on this topic. Landscape photography rarely needs wide apertures, so you can save a lot of bulk and money by not buying and carrying around f/1.4 options. You can decrease those costs and bulk all the more by opting for something like a 24-240mm superzoom. You might shy away from the thought of a 10x zoom, but they have made tremendous progress in image quality in recent years, and having to only carry one lens when hiking multiple miles can make a significant difference in your comfort. Check out the video above for the full rundown from Iversen.
And if you really want to dive into landscape photography, check out "Photographing The World 1: Landscape Photography and Post-Processing with Elia Locardi."
If someone is a "Landscape Photographer", they know what lens(es) work for them. If someone merely photographs landscapes occasionally, they'll use what they have. Either way, it's a hard thing to tell someone what they "should" do.