Create vision problems the same way Reksai's tremors create too much vision for her team? If Ww can globally track weak enemies and give this vision to his team, as a PASSIVE on a skill, isn't that too much free power? If Ww gets to keep his W's vision Reksai needs compensation.
Only warwick can see the trails, not his team, so there's no problems.
I'm guessing the difference is that only Warwick can see the bloodtrails, plus it never gives an exact location, only a general direction.
Rek'sai allowed for pinpoint knowledge of where the enemy was if they were in range, and also exactly how many. Not to mention, Warwick's vision only extends to those below a certain health threshold
In competitive play, most people aren't going to be sticking around for very long at <50% health anyway, or at least they'll be safe about it. Outside of laning phase it's hardly going to do anything anyway because everyone's going to be full health until a fight breaks out.
I mean it's just a general trail. In essence, you basically know 'There's a low HP person somewhere down/up and to my left/right' because it follows just click pathing. For isntance, if you were on one side of the dragon wall, and they were 1 teemo across the wall in dragon pit. It'll not point AT the wall, but just where your champ would walk if you clicked on them. It's not very precise.
