How does this affect the community other than smaller accounts not getting up voted by those big accounts?

This deplets the reward pool which is produced at a fixed rate. Meaning that in the end all of our upvotes are worth less because they are taking a big portion of the pool.

At one point of time haejin was pulling an incredible 6% of all rewards.

We can only speculate on the destructive effects of their greed on the future of this platform but they are surely not good.