Blocking a PR can also be toxic "depending on the circumstance".
I see zero toxicity in leaving comments without blocking. It's never prevented the people I've worked with from getting work done.
I've worked at three large tech companies and none of them had this "block PRs" mentality but they all got stuff done. The reviewers understand their roles: they leave feedback, if there are questions, they answer them. If the feedback's handled, they re-review.
It works exactly the way you say it should, minus the "blocked/changes requested" status on a PR. Maybe precisely because we understand that a PR is blocked until it's approved anyway, and the green check is the goal.
All the opportunities for dysfunction are the same: people can still bikeshed, they can not review, they can not come back and re-review, etc. None of that is affected by the "changes requested" vs "comment" dichotomy.
Frankly, the "we can't collaborate without blocking PRs" take seems strangely dysfunctional to me.