While the upgraded 747-200B's (Japan Airlines was the primary user) could fly from New York JFK to Tokyo Narita nonstop, they were not the ideal solution due to the additional fuel capacity reducing the cargo space capacity. That's why Boeing developed the 747-400, which had far more fuel capacity without sacrificing passenger or cargo load.
And once the 747-400's were available, the value of 747SP's plummeted. An airline using a 747-200 with extra fuel tanks could at that point take out the fuel tanks and use it as a normal 747-200, while a 747SP couldn't economically be converted to other uses.