Does it? Have you seen the actual text and what it says?

What actual text? These were negotiations, not finished deal documents ready for signature. Neither side has released any "text," which is why you haven't read any "actual text" and what it says either. No draft text was ever published, as is customary for these types of negotiations (no matter who they're with).

Canada's stated reason for walking away from the talks was the US insistence on having increased control over Canada's ability to enter into trade arrangements with China. Under those circumstances, it makes a ton of sense for Canada to reject the agreement. And when you combine that with Trump's demonstrated tendency to upend existing trade arrangements on a moment's notice (Fentanyl! Wildfires!) there's not much "win" for Canada in a putative "win-win."

It's a cornerstone of negotiating. "Never enter a negotiation you're not willing to walk away from."

We're trying to lock up the Western Hemisphere's supply chain provenance and make it less reliant on China. Why this is a bad thing in certain intellectual circles is beyond me.

It's not really hard to understand. Canada doesn't want to be "locked up" with the United States. We wouldn't accept a third-party trying to lock us up, and they don't want to be "locked up" either. They want to be able to determine for themselves where in the spectrum between autarky and absolute dependence they want to land with China - and the US and the EU and every other country. Not every country will reach the same conclusion about what level of reliance on China is in the best interests of their citizens, and Canada certainly doesn't want that decision to be made by Washington instead of Ottawa. Especially since the pros and cons of being part of that "locked up" Western hemisphere are very different if you're the dominant party, like the US, or a much smaller country like Canada.

So sure - it's great for the U.S. if we lock out every major economy but ours from the Western Hemisphere. But if you're one of the other countries in the Western Hemisphere, if the U.S. is going to be aggressive about leveraging its size against smaller countries, you absolutely do not want a world where the Western Hemisphere is "locked up" and you are stuck with the U.S. You want to keep your options open. Not sure why that's beyond you - it seems pretty straightforward.