Try not to think of it that way. The community is the people who subscribe, post and comment. You don't own them, you just take out the trash. If they are happy to move then good, if not then don't force it. And you can always just make a second community on the other instance and hand over the old instance to the people who want to stay there.
I don't know what it is, maybe it's some form of ikea effect, where people think that the act of filling a form, adding an icon and a description makes them immediately attached to something that (initially) amounts to a record field in a database.
I've lost count of how many people I asked "Hey, I saw you are the mod of <mostly inactive community on large instance>, I am running <slightly active/mostly inactive community on topic-specific instance>. How about we join forces?" And almost invariably they act like I am asking them to give me their firstborn.
And almost invariably they act like I am asking them to give me their firstborn.
You can't infer that they are being possessive, when an equally possible explanation for that reaction is that they are offended on behalf of their community members, who would not want a unilateral consolidation of their community into another community that they feel no connection to.
Just because you mod a community doesn't mean you get to make the decision about where people gather for that community. When instances have different moderation rules and different vibes, you must have a consenting userbase in order to make decisions like that.
I'd definitely like that as a programming.dev user. I like to see topic-specific instances used for that topic, and to have lots of communities about that topic.
Can someone please explain what the issue is with lemmy.world? I signed up 2 years ago and haven't been very active and just recently came back to lemmy in general.