People that try out new champs in ranked?

I had this Gangplank on my team and he went 0/11/2 in under 20 mins. when i looked at his profile, he had decent mastery points with 3 other champs that werent even toplaners. why are there so many people that try out new champions in ranked. why not play normals instead. thats where i go play when i want to get better at a new champion or improve my skills. i hate that in silver elo most every game i come with a team that doesnt even have the lvl 4 mastery icon, im assuming that they are smurfing if so, but no; they just suck beacuse they dont know how to play that champ. there should be a system in Ranked that made it so you could only play champions that you have upped to lvl4 and so on. what do you think of this system? i really dont see any downsides with it.