> - A big queue of PR's for reviewers to review

This is a feature. I would infinitely prefer 12 PRs that each take 5 minutes to review than 1 PR that takes an hour. Finding a few 5-15 minute chunks of time to make progress on the queue is much easier than finding an uninterrupted hour where it can be my primary focus.

> - The of the feature is split across multiple change sets, increasing cognitive load (coherence is lost)

It increases it a little bit, sure, but it also helps keep things focused. Reviewing, for example, a refactor plus a new feature enabled by that refactor in a single PR typically results in worse reviews of either part. And good tooling also helps. This style of code review needs PRs tied together in some way to keep track of the series. If I'm reading a PR and think "why are they doing it like this" I can always peek a couple PRs ahead and get an answer.

> - You end up doing work on branches of branches, and end up either having to become a rebase ninja or having tons of conflicts as each PR gets merged underneath you

This is a tooling problem. Git and Github are especially bad in this regard. Something like Graphite, Jujutsu, Sapling, git-branchless, or any VCS that supports stacks makes this essentially a non-issue.