As far as I can tell this isn't true. Mount Everest can be seen from Kathmandu but not from the city center as it is obscured by Kang Nachugo see this image: https://i.imgur.com/4N3gs5V.jpg
If you got to the south of Kathmandu e.g. Chobar where this photo was taken, Everest is no longer obscured as seen from this image https://i.imgur.com/JCMmhTs.png where the line between the Everest summit and Chobar is seen passing Kang Nachugo.
If you got to the south of Kathmandu e.g. Chobar where this photo was taken, Everest is no longer obscured as seen from this image https://i.imgur.com/JCMmhTs.png where the line between the Everest summit and Chobar is seen passing Kang Nachugo.