Why is Blitzcrank still in the game?

Blitz is literally centered around a single ability that takes zero skill to use. His base damage is high and he'll take at least 50% of your HP in a combo early game. The ADC literally has to AA two or three times and the job is done.

Now, this isn't a post about Blitz being overpowered or not, it's simply a post that wonders why such a champion even exist? Riot frequently reworks/changes champs that are unfun/frustrating to play against. Why hasn't Blitz been changed?

The only real way to play vs. Blitz is to play extremely passive. It's so frustrating and boring that I cannot fattom why he's in the game. He's the epitome of anti-fun and should get reworked. No one likes playing against this piece of crap champion.