The vast majority of people who are visiting subreddits are doing so because they're actively seeking out the material being presented to them. These people are subscribers to the subreddits. Subreddits that "go dark" are not blocked for everyone. Their access is restricted ONLY for those who have not yet subscribed to the subreddit.

So this giant display of enlightened asshattery affects almost nobody. And even if it did, it's a 2 day ordeal.

Which means jack fucking squat. It's the equivalent of wearing an MLK bandana on Juneteenth day and spending the rest of the year voting and campaigning for politicians trying to abolish what's left of the Voting Rights Act.