But the thing about marriages is they’re unimportant until they suddenly are, so understanding the full picture is important even if most arrangements are an afterthought. Some will be with people who hold no claims or titles, others will lock you into alliances.
There are so many people you can arrange marriages for with far too many characters in the world. On one hand they hardly seem that important. Marriages in a game like Crusader Kings 3 are a bit weird.