why is autofill on in bronze?

bronze has 50% of the player base. why in the hell is autofill on? dynamic Que was put in place so people could play the roles they want. instead of the old way and getting forced into support because they were last pick. if dynamic Que is so great according to riot then leave autofill off in bronze when its not needed. it makes toxic teams when you get the support spot picking master yi or some nonsense. i main adc bot lane and mid lane