capacitors: why is the dielectric constant defined the way it is?

usually when we have some initial variable U(0), and we have some factor K that changes this initial variable, we usually express the new variable U(f) like so..

U(f)=KU(0)

and NOT the other way around...

so why is the dielectric constant expressed in the following way?

Eκ=E₀

this doesn't make any sense to me