The talented young striker is imminently set to secure a £23.5million move to Sheffield United and Klopp has explained the thinking behind allowing Brewster to move on centred around his development.
"Rhian couldn't make it here, so far (into the first team)," Klopp said.
"That's pretty much the information. But he has made big steps in his development.
"Rhian was seriously injured, so first and foremost we had to make sure he was ready for all the demands of professional football again and he is now 100%.
"He had a really good half season at Swansea and was really impressive, he came here for pre-season and scored for us - you could see that he made big steps.
"It's about development - if Rhian was now 25 or 26 we would say stay and work for your chance - it's a different situation when you are younger.
"A player like Rhian in this position, it's important he makes the next steps and uses the time he lost during the serious injury.
"It's possible a move to another club would make sense but I don't know exactly what will happen there.
"If Rhian stays this year, he's part of the squad as well just like Curtis [Jones] in the same way. It's about earning game time and you earn during game time during training and the minutes you get.
"We have to find the solutions for different personal situations. We try to help the players do the right thing.
"Sometimes it's a loan, sometimes it's a club that wants to buy the player.
"It's not about the number in the squad, I can work easily with 24 or 25 players for a long season, but if the player doesn't feel comfortable in the situation fighting for a place or doesn't see the perspective, then we have to talk.
"These kinds of talks are going on at the moment but like always and then you will get the result in the end when a decision is done.
"Sometimes it is just better for a player to go somewhere else and get more game time."