As dissidents, we have to know a lot. Wherever we go, people will want to address every single aspect of our dissident ideas from the surface to the foundation. Our answers not only need to be good, but we need to have the source on hand. We need to be able to discuss biology, history, and sociology, and current events. There is a lot of social cred to "pwning a racist" so we need to be on point at all times to everyone.
The opposite is true for liberals. There are massive social penalties for disputing their core ideas. You can dispute their tax plan, but you will raise eyebrows if you suggest that race is real, and you'll get fired from work for suggesting that genetics explain disparate outcomes better than the environment does. You might get assaulted in the streets if you suggest that whites take our own side. For that reason, they can get away with a lot of shit without being really scrutinized. Not only does this mean that they don't have proper incentive to learn about the world, but because they don't see their opposition, they just assume our experiences must be like theirs.
Interestingly though, liberals are self aware about how little they know. It's not like they think they know of an actual multivariate analysis that explains away the IQ gap. It just never occurred to them that they'd be asked for one, or even that this is how debates are had. They don't think that they can argue their beliefs, but rather that someone somewhere could, if only he were here. They think that the terms of engagement are that neither debater knows anything, and that knowledge is over there in science world where we can't look at it. When we stress actual research, they think it's foul play because we violated those terms.
The problem is that when you give them real evidence that makes sense, liberals aren't convinced because they know that they have so little knowledge that even if there was a good counterargument, they probably wouldn't know about it. The average liberal never thought that they could defend liberalism on a genetic basis; they just never thought they'd be expected to. They think that we're "cheating" when we talk about studies, because they think we're asking for this weird obscure thing that nobody is ever actually expected to have. They know that they're on weak footing to argue, so they're unimpressed when you win an argument against them. They think: "It's not that he's right; it's that he prepared for this and I didn't."