I think we have different opinions on how "improving" applies to League. I don't care about my rank. Hypothetically, if I had the skill of a Diamond Anivia player and my Aurelion Sol and Lucian were Bronze, I would not feel like I deserved Diamond by only playing one champion.
I also think it is important to master several champions because certain matchups are simply not winnable for Anivia. For example, it is essential for midlaners to learn an AD champion in order to be effective against Kassadin.
I came here because I recognize that most of my midlaners are niche picks, and I want to expand my pool so that I have more to offer to my team, especially in Clash. I do not find that your comment contributes anything positive to this discussion.