If Kerenzikov is "not that powerful" why is it costs 4D6 of Humanity?

If I am remembering the lore of speedwares(Sandy and Kerenzikov both) correctrly, they can't really "slow down" time that much like in 2077 game, or Edgerunner anime.

Kerenzikov work by speeding up your reflexes 24/7, but in TTRPG, it only gives you +1/2 to initiative roll primarily due to balance reasons(opposed to modifing DEX stat).

My question is; if Kerenzikovs aren't slowing you down that much(considering even DEX 10 is within human parameters), why does it costs 4D6 humanity?

Is it for balance? To stop players "spamming" Kerenzikov to their characters?