That's why you need to sear the steak first, to keep those delicious juices in.
That is not true !
You can very easily do the experiment to check:
get two steaks from the same cut, and approximatly the same weight.
Sear one, fry it for a set time and weigh it.
Just fry the other one for the same time, without searing it, weigh it.
Now compare - the seared steak will have lost a lot more weight.
The better taste comes from the Maillard reaction - a kind of caramelization.
In short: colour gives meat taste.