Non hindi singers

Why do judges promote singers saying they do not know hindi well but are still doing well. This is a hindi reality show. Hindi is india's national language. The contestant n every indian is expected to have basic knowledge of hindi. Even if some of them do not know hindi that well, it can't be a topic of discussion or reference. It's wrong and also unfair to other contestants. I expect the judges to encourage such contestants to acquire that knowledge. It will ease their future performances n it will be helpful in their career too. It's upto them to learn or not to learn hindi. But on part of judges it's completely WRONG.