Does this ever happen? It seems to me like every time someone says something unpopular, the world goes on a witch hunt to destroy that person's life. That's not what I call "constructively challenged". I call it "just short of hanging them, which is what people really want to do."
I'd love to see a world where I could debate a matter with someone without everyone getting so emotionally charged that logic gets thrown out the window, and ideas that are incorrect can be pointed out to a person without everyone hating one another.
Every time I've witnessed a "debate" where people "constructively challenge" people who have opposite views, it ended in a shouting match.
I'm happy to avoid any such "debate." In my experience, the kind of debate you describe tends to happen far more often between people who have (paradoxically?) similar views, and who just like to explore ideas and challenge each other.
That intellectual trait is completely orthogonal to the views themselves. The closest thing I tend to compare it to is the charity principle, but that may not encapsulate everything quite right.
It used to be that you lived next to your neighbor and you had to talk to them or at least acknowledge their humanity even if you disagreed. In the early days we all heralded the internet as ushering an a new era of enlightenment and democracy with freedom of information for everyone.
Of course the reality is that when there was only one nightly television news program, those creators felt some responsibility to report objectively, and no pressure to pander to some demographic. Now, anyone can get any view point they want at any time. There is no value in thoughtful, reasoned opinions because that doesn't resonate with a highly opinionated audience—it's better to be loved or hated than passively respected. You don't have to talk to your neighbor at all because you can literally stare at your phone every time you are outside. No one ever has to hear an opinion they don't like, and when they do they can find their own bespoke mob to initiate a witch hunt.
Technology has enabled us to have a civil war without needing to be divided by a physical border. The tribes can coalesce from arbitrary locations.
"Echo chamber" is a deliberately pejorative term, which I think is unfair here. If you use Twitter to discuss your beliefs, then, yes, it functions like an echo chamber, and that can be a bad thing because when your beliefs are wrong, they won't be constructively challenged.
But I generally use Twitter to discuss my interests. Sure, the line between the two is fuzzy, but I think there is a difference. I love pixel art, and follow a lot of pixel artists. Does that make my feed a "pixel art echo chamber"? I guess so? But that seems to me about as harmless as joining model railroad club.