@Jeeha0 *IF* is the active word here.
I fully understand what the problem is, it's been talked about at length by many people on this forum. You seem to be assuming that I'm not grasping what you're trying to communicate.
Restricting people from matchmaking until the squad they left in the last game is finished is not the best approach, because - as I stated above, the person who gets left alone to play the match could last another 15 minutes - or even right to the very bitter end.
How would you feel if your game crashed or you got an error and then you couldn't play for 15 minutes because of something that is completely out of your control?
Sure, you could go make a sandwich or find something to do... but what happens when you join another match and you get another error/get disconnected and have to wait another POTENTIAL 15 - 20 minutes - for something that was out of your control. Is that fair to you?