A bunch of scientific papers are probably better data than a bunch of Reddit posts and it's still not good enough.

Consider the task we're asking the AI to do. If you want a human to be able to correctly answer questions across a wide array of scientific fields you can't just hand them all the science papers and expect them to be able to understand it. Even if we restrict it to a single narrow field of research we expect that person to have a insane levels of education. We're talking 12 years of primary education, 4 years as an undergraduate and 4 more years doing their PhD, and that's at the low end. During all that time the human is constantly ingesting data through their senses and they're getting constant training in the form of feedback.

All the scientific papers in the world don't even come close to an education like that, when it comes to data quality.