Because, while we know how shitty Reddit as a company has behaved, there are millions who have no idea (despite the popular posts by mods across thousands of subs) and now feel that the mods and subs which went private/restricted are the ones damaging Reddit, rather than Reddit shooting itself.
To be honest, not that many people seem to actually care and I think this would have gone better if they didn't announce their "for 48 hours" bullshit. Imagine if the WGA said they were going on strike for two weeks and then getting back to writing. They would accomplish literally nothing.
Subs saying "for 48 hours" is the equivalent to that. If they just went indefinite from the start, they wouldn't have to be polling people who are now mostly just annoyed that their experience has been unpleasant for two days.
Honestly, as much as I support the whole thing, it went about as well as expected. Mods kind of shot themselves in the foot, now the community blames them.
In a way, those users are right. Either go all in or do nothing. Middle-of-the-road shit doesn't work for things like this.
Also, the constant image with the black background and large white text saying Reddit sucks (that's at least how it appears to general users) is becoming literal spam. Regular users see it, and it becomes one of those things where it's like "we heard you the first dozen times, please shut up". Also, because it's being spammed, it loses impact and people gloss over it or filter it out.
At best, they'll annoy enough people to leave (kind of roundabout way of accomplishing things, but I guess it works). At worst, they've given reddit a reason to declare the mods as promoting and engaging in spam which "doesn't benefit the users of the site, so we're going to step in and get things back on track so everyone can enjoy Reddit" or some corporate shit.
Honestly, Reddit's in a position where they may even have the upper hand now in terms of PR. Users angry, but not at them.
The thing is, the people who don't realize what this is about are going to be having a really rough time in a couple of weeks when moderation slides. Of course, they're going to blame the mods again and say they're doing it on purpose because the "protest failed and now you're just being spiteful and hurting the users".
We know that's not the case. The majority doesn't and won't care.