About Tahm Kench's passive...

When Kench lands an attack, the enemy gets a stack from his passive, right?

But is there a reason why there is no countdown from when the stacks start to expire? If you don't know what I mean, the icons above your HP bar, abilities, etc. Has little icons to display your buffs, debuffs and tells you stuff about stacks.

Jinx has to build some easy stacks to increase her attack speed when she has her mini-gun. They also show a mini countdown from when the stacks will start to drop off. So why isn't this the case for Kench's passive? Different mechanic I know, but it should be given the same kind of treatment, in my opinion.