In the most polite way possible: The community is not yours. The content you so badly want to extract quickly, for better or for worse, belongs to the communities on the other instances, and while your users can easily join and contribute there, that’s not what should be the sole value/reason people join your instance.
Lemmy (and the Fediverse at larger) is intended such that like minded people can congregate and discuss on subjects that are pertinent to their interest. The right way should be to subscribe to content you intend to read, bring like minded people who are interested in similar contents you read to share your instance, and then grow organically from there.