It isn't as simple as realism versus B. Why?
Because you can be a realist about different things.
When you do a spin "measurement" on a spin 1/2 particle you get two results. And ... you leave the particle in a new state. We know this because if you prepare a thousand systems identically they have a whole fraction that give you one result and a complementary fraction that gives the other result.
But after the "measurement" you get a new thing, a thing that for sure gives the same result if you measure it again. So the original gave that result just a fraction of the time, but the new post-measurement result is different since it gives that result 100% for sure. So measuring it has actually polarized the particle into a new state that is different than it was before.
This is common in everything we call measurement in quantum mechanics. Yet even though this interaction changes thing, since the word measurement is used people want to pretend that it revealed something that already existed.
Even people that want to call themselves realists sometimes want to pretend that, even though it clearly is false. So some people aim for a kind of realism where they want the knowledge (which of the two results you get) to be determined by some spooky realist kind of thing.
Other realists are willing to be realist about whatever it takes to get results that agree with experiment. They are willing to allow the results of those "measurements" to be determined by realistic things that also include things more than just some preexisting up/down.
After all if you write down the Schrödinger equation for the actual experimental set up you will see that there are different devices that can take the same beam of identically prepared particles and get the correct fraction having the correct results (deflect the beam into distinct separate beams with the current total probability current). But yet these different devices send different portions of the probability current onto the different paths.
This isn't a question of interpretation, it's just how the Schrödinger equation evolves an incoming beam and how the probability current density has streamlines that go to the corresponding deflected beams.
So why should we expect a realistic picture to say that they are sorted based on their secret spin cheat sheet when ones with different secret positions (if the positions are realistic) are getting sorted into different beams while the spin becomes changed (polarized) by different devices?
You don't have to be realistic about position, but if you are there is no room left to be realistic about all these different devices merely revealing secret up/down results for spin. Instead you have to have a spin state that is realistic as an object and have it realistically be polarized and have it diverge these beams in different ways for these different devices. Because that is what the Schrödinger equation requires.
If you tell a realist what to be realistic about, then show it doesn't work, you just showed that you were bossy, not that realism doesn't work.
That said, the initial state can be nonlocal to begin with, so I don't know why anyone asked for a local theory to begin with. I guess if you thought the result of up/down was passively revealed them maybe it made sense to just as sign that to each particle in some kind of predetermination.
But predetermination is another issue, you can't control for predetermination if your attempted controls were predetermined as well. If someone picks there favorite kind of realism, then pretends that is the only realism and then calls something locality and then pretends predeterminism isn't allowed. Then they can contradict observation.
There is a sense where everything is local, they are local enough to have a PDE, but the domain is configuration space. And again, the initial conditions are that way, so I'm not sure how to get around that.
But to address your question directly now that we have the background. People have a good reason to prefer nonrealism. Just not a knock out like they might think they do.
What is the point of a realistic nonlocal theory? If someone far away can mess with your realist stuff then how can you make any local predictions unless you average away the influence far away people can have on your stuff. And once you've done that your effective theory discounts the effective reality of all that stuff, so why bother calling it real when it doesn't affect the statistical results you get averaging away the effects of stuff far away?