IMO, PRs were never the right process to use in tightly-collaborating teams such as most companies. PRs got popular because orgs started using GitHub, and GitHub had made that workflow to fit the needs of open source (and modeled it after what open source was already doing in the days when patches got sent around via mailing lists).

I'm old enough to remember using CVS and then subversion in companies. People would commit straight to main (which was then called "trunk"), because making feature branches and merging them was cumbersome. And, on regular intervals, the person responsible for some corner of the codebase would do a show-and-tell presenting it to peers, but without the sharply defined boundaries of what the code looked like before vs. after some recent set of changes. People might remember some things from the previous show and tell or from first hand experience with that code, but that kind of memory is necessarily fuzzy, and diffs weren't an artefact that was typical to look at. So, these reviews didn't block people, and any comments that came from reviews defined a direction that things should go from here on out. If a corner of the codebase was deemed to be in a bad shape, the blame around that was equally fuzzy.