the spawn player

Wy is there a payer json file in minecraft if you can,t spawn a plaer because i mean been able to spawn a player would be relly cool but if mojang does not want people to be able to spawn players then wy is the file there were people originally able to spawn players or did mojang i mean you guys think you made some kind of mistake but ive seen some maps with spawn players so did you just think it,s not for everybody and wy