To refute your points a bit :) ->
1. Debate itself is highly stressful, but pressure makes diamonds as they say. My time in debate made defending my honors thesis much less stressful and I’m a very calm presenter as a result.
2. This is exactly what debate research forces you to do. You may not get to choose your side, but you’ve done your best to prep in either direction. You get very good at understanding if the evidence provided has any gaps, and if it supports the impacts claimed.
3. Debaters do read judge profiles to understand the audience and determine strategy.
4. This is a major part of prep, as naturally you need to prepare both sides and understand the counter arguments at least 2-3 levels deep.
5. This occurs often, as mentioned in the article linked above. Ks and counter plans allow debaters to reframe the topic in many ways.
On your last paragraph: I experienced the opposite. Debate made me realize how ambiguous most issues are. While one team does win, the decision basis is often nuanced.
I will say that for my part, debate had a profound impact on my life. It taught me how to research, consider unintuitive perspectives, and articulate a point.
My research in debate directly led to a fellowship, honors thesis, and mentorship - all outside of debate. I leveraged my academic success into a great career and owe a lot to the skills I picked up on my college debate team.