Would smurfing and getting say bronze as a diamond player result in a permaban

We all know streamers, and youtubers intent feed to derank their smurfs. This is not okay. But to get a lower elo, would you be allowed to play a role you are not proficient in, in an attempt to learn the role while not butchering your rank on your main. Most high elo players are high elo due to their massive skill on a single role, so say if a Lee Sin OTP played only leona jg, and went from masters on main to B2, would he be banned? answer please riot.