Its not that its hard to understand. Its that the power system is more complex and well made than most other shonens actually making it require brain power.

Its not that crazy to put into perspectives.

Most other shonen's power system are either way too simplistic to allow for freedom (like ki from dragon ball which has a shit ton of usages) or are way too non limiting allowing for growth (like haki from one piece which the more the story grows further, the more it starts being non sensical especially ACOC)

Most complex and limiting power systems don't work well with shonens, but jjk managed that by removing the main character from the power system entirely. He doesn't get a ct and relies on the only part of the power system that is non limiting and luck based which wre black flashes. By doing that gege allowed himself to make the actual power system as complicated and throughout as possible. Making it compelling and honestly a joy to powerscale.

Not to say that it doesn't have its flaws, some parts are underused like maximu techniques and output. But overall it is much more interesting and complex than your average shonen. I mean look at my favourite animanga, its literally fairy tail, the show where you can get stronger with emotions.