Why do we say “dehydrated” when “hypohydrated” describes the state?

I was thinking about the words dehydration and hypohydration and something started bothering me.

From what I understand, dehydration is the process of losing body water, while hypohydration is the state you’re in after you’ve lost it.

So why do we say someone is “dehydrated”? If dehydration is the process, shouldn’t the person technically be “hypohydrated” once they’re actually in the water-deficient state?

I know “dehydrated” is what everyone normally says, and I’m not talking about common usage. I mean strictly speaking, doesn’t that mix up the process with the state?

https://redd.it/1x0z2hc
@r_etymology