Rationality is out the window at this point. This is the culmination of several different lines of action and unaddressed grievances. It is unfortunate that this is the final straw.
Some of the subreddits banned were in fact not hate subreddits. NeoFAG (admittedly poorly named) was dedicated to criticizing NeoGAF, another website with shitty admin. I wasn't part of it myself but it probably had to do with gamergate. Add to this, reddit CEO Ellen Pao often makes statements characteristic of "social justice warriors" and has stated her intent to make reddit a "safe space".
Many major subreddits are now effectively controlled by special interests. IAMA and AMA are basically just celebrity only when once they were open to anyone willing to talk about their experiences. Someone identified a set of keywords that prevented any post from ever rising in r/technology. Essentially, where there was once discussion, there is now enforced conformity.
One of the biggest, though, is the "shadowban". Used to silence critics of reddit, people with different political opinions and even people just promoting their own things. That last one is surprisingly important, because it basically meant that few content creators could ever hope to gain popularity. The shadowban is generally an unsavory tool and while it originally was intended to prevent bots from identifying that they were banned, the administration started using it very liberally.