> That, however, is not the only way to use the tool
And “pull request” somehow is exclusionary? No, because you can use it to talk about both inter- and intra-repository changes.
And it also handles the cross-repo case, which is a common case in the Github model of "make your own personal fork of the upstream repo and send PRs from there," which has advantages -- it allows random people to send PRs without needing to give them permission to e.g. pollute the upstream repo's branch namespace.
Though I agree the situation is somewhat muddied by the fact that you can create pull requests for branches in the same repository (even though that's not the normal workflow). GitLab's "merge request" terminology is more accurate for that use case.
If I pull your code, your code goes to me. If I request that you pull my code, my code goes to you.