Terrible slow motion moments

While the movie has more than a few problematic areas in it's creation one thing that really bugged me throughout the entire thing was all the unnecessary or just awfully-executed slow motion. Why on earth did the film-makers decide to use so much speed-ramping when they clearly weren't using high-frame-rate cameras to pull it off correctly? There are so many places in the editing where the film suddenly goes into slow motion and it's clear they are just holding frames longer than their intended 24fps. It stands out a mile and looks amateurish and cheap despite all the high production value in other areas of the film. Cannot understand why they chose to persist in doing it.