Spellbinder design is counter intuitive if you think about it.
The item takes forever to stack on your own and is best stacked in team fights.
The problem is each team fight you are actively choosing to do one of two things.
- Pop spell binder because you have enough stacks. Or
- Use this team fight to stack spell binder.
That means spell binder active is not used in every team fight, but in every second or third fight. Maybe in a 1v1 situation you might pop it because its stacked. Even with Ignious hunter cutting the cooldown to half, you still have to stack it for it to be remotely effective.
The point is, the active is rarely ever ready for a team fight or reliable.
When you think of it like that, does the 4 second active even seem to be worth it? Even when you wait patiently and stack it to 100 for that perfect moment, is 4 seconds enough? Does it ever feel super impactful considering the dedication you took to stack it?
etc. etc.