For the sake of argument, let's say you have a check that caps the number of lines per file and that both you and main added lines in the same file. It's not too weird if that check fails only after merge, right?
One benign example of something that can break after merge even if each branch is individually passing pre-merge. In less benign cases it will your branch merged to main and actual bugs in the code.
One reason to not allow "unclean merges" and enforced incoming branches to be rebased up-to-date to be mergable to the main branch.
You probably want to run the checks on each commit to main in CI and not rely on them being consistently run by contributors.
You do you but I find rebasing my branch on main instead of merging makes me scratch mybhead way less.
One benign example of something that can break after merge even if each branch is individually passing pre-merge. In less benign cases it will your branch merged to main and actual bugs in the code.
One reason to not allow "unclean merges" and enforced incoming branches to be rebased up-to-date to be mergable to the main branch.
You probably want to run the checks on each commit to main in CI and not rely on them being consistently run by contributors.
You do you but I find rebasing my branch on main instead of merging makes me scratch mybhead way less.