Assuming the criticism is true, would an edited version put US history in a much brighter light?

Probably not, just a different one. The AskHistorians threads about this are typically accompanied by more credible left/populist histories; Jill Lepore, as an example.

Exactly, so to focus on dismissing the book/author seem very opportunistic since the core of the argument is still based on facts, and people should acknowledge the bad parts of their history.

I'm sorry, I don't understand this response.

That people should discuss the issue even if one account of the issue is only 90% correct. People seem to be deflecting.

The story is about Zinn. If anything, the deflection goes the other way.

Given that I’ve always seen AskHistorians as an example of one of the best places on Reddit, and given how heavily moderated it is, do you have a more concrete criticism of that sub?

It's a good thing I cited a Democratic Socialist Professor of History at Georgetown, then, and not Reddit.

Yes, indeed. The vast majority of Redditors, bots. Some quite clever, actually.