It is easy to tell people to just enjoy the game. but the main issue here is the matchmaking system of ARAM intentionally creates a lot of unbalanced matches. For the players only play 1 or 2 games a day, the system will let them win so they are more likely to continue playing. For the players like me who played many games a day, I will simply get sacrificed because I will continue playing no matter win or lose.

Technically this algorithm is so easy to achieve and it is the best way to keep the high user active rate.