End of Season Rewards

Why is it based off of whatever you end on instead of peak ranking? I don't know about others but for me personally it discourages people from playing ranked after they hit the next tier out of fear of dropping rank and not getting the rewards for the tier they reached. I may only be Gold 5, but when I look at the other people in my division all I see are people at 0 LP not playing ranked for what I can assume to be the same reason I am not. I feel like if you reached a plateau you should still be rewarded for reaching it. If it wasn't based off of current ranking I would continue playing to see how far I could actually climb rather than stopping dead in my tracks because I don't want to lose the rewards I've already earned.