Those cons you mention definitely do exist, they're an emergent problem of the conversations and communities that arise, but opinion bubbles never seem to be a bottleneck for a platform gaining popularity - which makes sense since they, by definition, favor the majority's opinion.

I'm also not convinced that chronological ordering is better for diversity of opinion: comments might not be hidden directly, but they can be drowned. In a reddit-like system each user can downvote you just once, while in a message board system each user can post N times, with each post making your opinion a smaller portion of the conversation.

What chronological posts are better at is favoring power users over casual users: there is a clear advantage for those who can post early and/or often. For everything besides the starting post of the thread, it also rewards short and not very thoughtful posts (since posting later is punished in visibility). The result is also a bubble, and one dictated by the people that spend their lives on the boards.

And in my personal opinion, there's not a lot of overlap between the people that lead interesting lives and are great at their fields and those willing to spend a great portion of their life in a message board.