If you ever worked with stacked PRs, and the top one gets squashed and merged it often becomes a nightmare to rebase the rest of the PRs to bring them up to date.
I wish this was easier. I have a workflow that I use to create stacked PRs which involves changing the target branch of the next PR to `main` after merging its predecessor, but it is too fragile to institute as a policy.
However, this is also just a more specific version of the general problem that long-lived, elaborate topic branches are difficult to work with.