It went against Washington’s policy of political neutrality, for one, and, for most of WWI, the US’s goal was to stay neutral. Many people criticized the plan because they thought the US was trying to exert too much influence.
The fourteenth point, the League of Nations, was very controversial. As with the rest of the fourteen points, many thought this point made the US too involved with foreign affairs, and many didn’t want the US to be responsible for keeping other countries in check. Ultimately, the US does not join the League of Nations, which leads to more criticism: why doesn’t the US join the League of Nations that it creates?