Your very premise is wrong. At any sufficiently large company, you are unlikely to be sitting in the same room as every collaborator and stakeholder, or even proxies for them.

As a simple example, the team I currently work on (on one project of several) is 10 people across 8 US cities in all four US mainland timezones, and the stakeholders and collaborators are across Australia, Asia, Europe and the Americas. A good majority of what I do is pair programmed, yet the pull request workflow is essential to letting _others_ know what is happening and why, and to allow them to have asynchronous input into the process.

You might argue it would be better for the team to be in a room somewhere. Maybe so, but the people this project demands live where they live and could not even agree a common location for that room to be if they wanted to. And it still wouldn’t help the other projects…

The goal in review is to try to catch any oversights or errors in the code you wrote. The code you wrote may have been the result of of discussions with your coworkers, but the code still gets reviewed, even if by people you discussed the implementation with. That review will occasionally find things you missed, and then you can cycle, and re-review.

By definition, the review can only happen at the end of change development.