Among other lenses, I have the 50mm f/1.8 and a 60mm macro lens. Not quite the question, but my observation is:
40mm, 50mm, and 60mm are all somewhat telephoto on DX. Indoors, shorter wide angle is popular.
Many zooms will substitute for a 50mm lens (many include 50mm field of view).
ISO will substitute for f/1.8 light gathering (today, not so true in film days).
A telephoto will substitute for background defocus of f/1.8. maybe better.
But nothing substitutes for a macro lens, to focus close on so many things.
Frankly, I rarely consider using my 50mm f/1.8.