Progressing in skill
I've lurked around this subreddit, the rhythm game subreddit and other sources and found that for chunithm specifically, the general consensus is to play what you can comfortably SSS and occasionally play higher charts. Why is that? I feel that for most other rhythm games, the general advice is simply to slowly move higher in levels and sit around those that you can comfortably clear. But in comparison, the bare minimum for chunithm is around an S+ whereas an AAA is considered barely scraping by.
TL;DR: Why is chunithm so much more focused on a seemingly quite high score for progression more than slowly moving higher in difficulties with something like S+ clears?