Ah, you found the work of Kevin Duffus, author of The Last Days of Black Beard the Pirate. He has done a lot of work researching Blackbeard over the years (I think it's approaching a decade now). His work with primary source documents rivals, and sometimes surpasses, work done by previous historians who worked on Blackbeard (but didn't interrogate the sources anywhere near as much, and as a result letting a lot of the romanticism and legend get in as fact).

it seemed to suggest that he'd capture and take over slaver ships and just leave the slaves with the boat and take the valubles and even recruit some of the slaves to his crew, never stating that he took the slaves as something to trade/sell

He did leave some behind, but his crew and him kept a picked group of them - and the evidence that ardent researches such as Duffus have revealed - that these black men were kept as slaves, either as a kind of plunder they could sell/barter with later, or to do menial work onboard. Also, sometimes, there wasn't enough room for all the slaves, especially when there might be hundreds of them on a captured slave ship. When Blackbeard split up his crew in 1718 and went to Bath, he kept about 60 black men/slaves with them. There is documentary evidence of several slaves being sold to local North Carolinians by Blackbeard's crew. Blackbeard appeared to have four or five under his personable ownership.

So I'm wondering if they glossed over that to make him seem more like an anti-hero instead of a villain

Problem is, pirates have gotten a bad rap until recently in terms of receiving serious study by scholars. They have also been romanticized. At this point, we are into the second generation of researchers working on pirates. The first generation, unfortunately, mostly locked onto the "radical pirate" interpretation for how pirates acted, was still working on shaking of some of the layers of romanticism that pirates are caked in, and concluded that most pirates were these egalitarian places where everyone was equal - and offered a beacon of hope for African-descended men. There is one historian, Arne Bialuschewski, who has written two articles on the topic of Africans and pirates. To say the least, black men were in a gray area. Maybe some of them received respect and were part of the crew (probably because they had maritime skills that the crew could use - and who knows if they still might be sold when convenient), but there is strong evidence that many black men found themselves still as property that would be used as basic workers and/or be sold for profit at the first convenient opportunity. The Madagascar pirates of the 1690s had strong connections with New York/New England merchants since said merchants wanted cheap slaves out of Madagascar (which the pirates could help provide, along with other riches taken from ships taken in the Indian Ocean, in exchange for supplies on Madagascar, or for trips back home to the colonies). For more on blacks on pirate ships, our r/AskHistorian's FAQ for pirate stuff has a question about this subject.

I tried so hard to find a pirate subreddit, like...an actual pirate one, but you can guess what I found instead.

Let me guess, you found the one called r/pirates? Unfortunately, that's a small subreddit and isn't that active. The subreddit for the TV show "Black Sails" is more active and has more members. You would have had better luck on facebook (where there are groups with membership in the thousands on there - I suggest the "Authentic Pirate Living History" group if you want the equivalent of r/AskHistorians for pirates on facebook).