This would be true if and only if GitHub allowed you to collaboratively review and modify the squashed commit message _as part of the approval_ process, a feature which I have been requesting from them ever since "squash and merge" became an option.
The teams I've worked on generally use a "copy the PR description into the commit message", which works well. And if there are oversights, the PR number is in the commit ID which is a link to the larger context.
It would be nice, but unfortunately it doesn't align with their goals - they want you to use github features, not git.
What I’m asking for is explicitly a GitHub feature - code review around the message that will be applied when you click the “squash and merge” button in GitHub.