The real invariant is responsibility: if you submit a patch, you own it. You should understand it, be able to defend the design choices, and maintain it if needed
Ownership and responsibility are useless when a YouTuber tells it to their million followers that GitHub contributions are valued by companies and this is how you can create a pull request with AI in three minutes, and you get hundred low value noise PRs opened by university students from the other side of the globe. It’s Hacktoberfest on steroids.
"You committed it, you own it" can't even be enforced effectively at large companies, given employee turnover and changes in team priorities and recorgs. It's hard to see how this could be done effectively in open source projects. Once the code is in there, end users will rely on it. Other code will rely on it. If the original author goes radio silent it still can't be ripped out.
Great for large patches, great way to kill very small but important patches.