iPhone Editor Wish List

Can you explain me something, please ? I understand why the lack of a RN editor prevents improvements of the mobile editor mode (e.g. "Tap on top of top screen in Markdown editor should scroll to beginning of note"), but I wonder if it also prevents improvements of the preview mode (e.g. "Increase preview font size"). Aren't the two issues different ? (Sorry if my question is stupid. I just try to understand.)