Why
That all I can say, even though I never really cared for the show as a kid.
I heard it was because the Five Nights At Freddy's Movie was soon to come out so they made this on a rush, to compete with it or possibly sabotage the Five Nights film by making the audience associate bad feelings/bad movie with bad, killer, animatronic monsters.
The irony is that if they had just focused on making a good film, a wholesome film that was family friendly they could have a lot more money and sabotaged Five Nights by taking away the scare/creepy factor with wholesome, goofy characters. Like maybe yeah the splits are animatronics that have come to life but instead of killing they just want to entertain and spread joy and love and happiness with song and dance.