When you say Rebel Moon has struggled with fans, what fans are you referring to?
If Rebel Moon Part 1 had a traditional theatrical release, it would have bombed.
It's getting strong numbers on Netflix, but this is already implied in the service itself. You can quantify Barbie as a box office juggernaut because people went out of their way, to carve out time, spend their money , drive to a theater, coordinate with friends, etc, etc, to go see it. This release was timed for the holidays, when people typically have some down time. They don't have to go anywhere to see it. And it's supported by Netflix's own bots, algorithms and internal advertising/marketing.
It's struggled with fans because the "word of mouth" is bad. There are lots of legacy shows like Who's The Boss and Growing Pains that would have been massacred if it was released at a different point in time. But there were only really three major networks. Most people didn't have cable TV. The competition was very thin. But it was accessible by just turning on the TV. You didn't need to travel, coordinate and spend more to see it.
At some point, you need "good word of mouth" All the marketing, virtue signaling, shock marketing and coordinated advertising roll outs can't stop the impact of basic word of mouth. Rebel Moon is going to fall under the category of "It's sort of OK, but you are paying for Netflix anyway, what else is there to watch?"
Now if someone said that Netflix's large scale competition is paying for or leveraging specific high profile reviewers or aligned publications/sites to pan Rebel Moon, then I'd agree with that. Netflix is now a big player and it's major competition wants them to suffer and burn. But again, nothing stops eventual word of mouth. So I don't believe all negative reviews against Rebel Moon are objective nor unbiased. But that's countered by the money Netflix spends to buy off reviewers, sites and publications as well. This is a silent "war" that works both ways.
Rebel Moons large viewing numbers on Netflix are not a lagging indicator of making fans happy. It's lagging indicator of the immediate raw benefit of implied proximity.
From the industry side, from a financing perspective, the only reason to make Rebel Moon is as a loss leader. To keep Snyder exclusively into the fold. This isn't much different than Fox green lighting Millennium, The Lone Gunmen and Harsh Realm, knowing that they'd all fail, just to keep Chris Carter happy since the X-Files, back then, was a legitimate television juggernaut and a real cultural phenomenon world wide. But this also has to consider that there is so much original programming out there. There becomes a major incentive for a network to keep, at high cost, someone like a Ryan Murphy exclusively.
Netflix is under a lot of pressure to create original content. To justify why subscribers should keep subscribing. If Snyder is here, it's because he couldn't make it outside of a system where the logistics favored a structurally flawed film. If you and Alatar and others love it, then great. You do you. I'm happy you found something you enjoy. But practical fan word of mouth for this is just not very good. But Netflix HQ knew that. Which is why Rebel Moon only got a very short window theatrical release in a small number of areas and venues.
Moving the goalposts or attempting to doesn't deflect from the reality that, at some point, a film has to be able to stand on it's own merits. But Rebel Moon, in the eyes of Netflix HQ is not a film, it's content. They'd love a huge hit on their hands, if they can get it, but they are more than happy to settle, as a consolation prize, for just more empty calories.