Reputation system

Correct me please if im wrong but reputation is global in steemit?
Why is it? Woudn't it be better with system where each user have reputation per tag?

I mean it's pretty normal that guy who produces a lot, good content for lets say "funnypictures" tag, not necessary have any idea about "football" or "robotprogramming". So why his vote on subject he is really good with and subject he probably has no clue about are equal?

Reputation system is to simplifited imho and should be rebuild. Reputation shoudn't give global power, it's just to dangerous.