It's good to understand how powers interact with each other, or tell a story imo. Power levels aren't absolute, but higher tier/stronger characters and people. Whether within vampires, or servants, or church people and what not do exist. Understanding how someone wins against another, and why is important to understanding the characters and the setting I'd argue.
In Shounen stuff. It's all about the flair and fun usually, so power levels are something you end up focusing on if the execution is lacking, and something you shrug off if there's plenty to enjoy I think.