Rebasing tends to induce more conflicts than merging, tends to lead to force-pushing which is often dangerous ( "--force-with-lease" is safer but a lot longer than "-f" ), and has to be done after PR review which bypasses one set of checks particularly in the case where conflicts have to be fixed.

presumably github will only let you rebase-merge if there are no conflicts. In my experience though rebase tends to have more conflicts requiring manual intervention vs merge, but that feels safer to me than merge occasionally automatically resolving the conflict incorrectly.

Github also has protection to prevent branches from being forced, if you are only forcing a feature branch with no collaborators, or at the end of collaboration, it's not so bad, especially when git tells you the old hash you just overwrote and you have the reflog, but again github's rebase-then-merge should make that a non issue.