"Because it's not actually all that much more fun to rule the entire world than to rule a country the size of Cheliax and because there are a bunch of gods trying to counterbalance each others' power and because there are random ninth circle wizards who can't be bothered to straighten out everywhere but who make it very clear that if you harass the peasants right on their doorstep then they'll dismantle you for parts, and because lots of parts of the world are too distant and rural and low-population and speak languages no one else speaks and it's not clear it's worth ruling them, and because empires don't generally grow past the distant limit of a Teleport, if it costs several it's incredibly costly to bring enough force over to keep your distant provinces in line."

"Because it's not actually all that much more fun to rule the entire world than to rule a country the size of Cheliax and because there are a bunch of gods trying to counterbalance each others' power and because there are random ninth circle wizards who can't be bothered to straighten out everywhere but who make it very clear that if you harass the peasants right on their doorstep then they'll dismantle you for parts, and because lots of parts of the world are too distant and rural and low-population and speak languages no one else speaks and it's not clear it's worth ruling them, and because empires don't generally grow past the distance limit of a Teleport, if it costs several it's incredibly costly to bring enough force over to keep your distant provinces in line."