Why Isn't There A 1922 Mercury Dime?

NO nickles, quarters, or half dollars either.
WHY?
The Pittman Act.
In a nutshell, the mint was so busy making Silver dollars, they didn't have time to make anything else.

Very interesting. But they did make 1922 cents.

No new dies made for 1922 cent either. They had to use old dies to try to make some cents. So the born of infamous 1922 no D cent with polished old dies.

Political lobbyists.

And 90 years later you thought it was a new problem

The silver dollar coin was rarely used in commerce then, but rather was used to back paper money and as reserves for small banks. Due to the recession and coin glut the nation was flush with subsidiary coinage so there was no need for most coins except cents to be made.

However, silver and mining interests in the western USA conned/bought off or otherwise convinced Congress to sell a quarter billion melted silver dollars to Great Britain and coin newly mined silver to replace them. This also helped keep the mint's staff busy.

1816 is very scant year as well. Due to a fire at the mint and being the "year without a summer", the only coin minted was the 1816 large cent. It was made from planchets, oddly enough, imported from Britain.

As One50 said, the Pittman Act. The econony was in a recession after WWI and there was little demand for coinage, but the Pittman Act required the 250 million silver dollars melted down and sold to Great Britain to be recoined. By recoining the silver dollars the mint employees could be kept employed and busy, plus the silver dollars produced allowed the government to reissue millions of dollars worth of silver certificates back into the economy as a stimulus. (When the dollars were melted down the government had had to withdraw the silver certificates from circulation because they no longer had the backing for them.)