There's an interesting story behnd that.  In 2007, the National Taxpayer Advocate held a forum in Omaha (across the river from Iowa, a farm state whose Senator Grassley was a Big Kahuna on the Senate Finance Committee.  Someone asked why there was not a line on Schedule F for office in home, like there is on Schedule C.  She thought that was a great idea, called back to Washington and in a couple days get the forms branch to agree to the  change.  She bragged about the fast action at the next forum she held, in Phoenix.  When the promised line never appeared, I asked several times what happened.  Eventually I got the answer that it was decided (by someone) that the line was not needed after all.  

(File under "Deep State.")