This is really oversimplifying things. The entire Market line of buildings is good to build if you have the production to spare, and unless I'm doing ICS, I can't see skipping Temples. Monasteries and Mints, if available are great buildings.
And really, at 4 gold per hex, Railroads are super expensive. Just imagine how many buildings' maintenance you could pay for by skipping a few tiles of railroads. Again, this might be just because I do everything in my power to have the vast majority of my cities be Coastal.
The railroad's mobility benefit is also somewhat reduced, because in some circumstances, one or two of your units on a railroad track can also potentially block other units. It's a minor point, but it's also irritating if it catches you at the wrong time.
Just another reason not to go nuts on them unless you can afford it (in which case you're probably well on your way to victory anyway).