No, it really isn't.
Differences:
1) Reddit is super ban happy, and there is no way to view banned content. Ban reasons include slurs, political opinions, as well as no reasons at all.
2) Subreddits are not filters over the same content, they have (mostly) different content.
3) There is a fractal abundance of user-moderated subreddit; yes, there is some bad culture in some of them. This is not what ACX is proposing. He is proposing 2-20 filters, ran by the company, not by volunteers, with a specific purpose and clearly defined.
I really don't see how ACX's proposal can cause illegal behavior or harassment that is not already there.
You're making a false equivalence with reddit, then pointing out reddit has negative emergent properties.