This method also seems like it may fall victim to the Dunning-Kruger effect; team members who should be "asking", or at least "showing" their work, but default to "ship it" under the impression they know what they're doing and just want to get it done and move on.
I like the concept in theory, but it relies almost entirely on the personal opinion of the submitter, and I'm not sure the submitter is always the best judge of what level of review their own work requires.
When you say "changes so big" you think your solution is better.
I am working in an organisation with so called "seniors" and their PRs are approved because other seniors made them friends.