I think it probably makes sense to host similarly moderated content together.
programming content being grouped together makes sense because it’s moderated to a similar extent between languages and communities.
For example discussions/posts on rust programming and porn are moderated very differently, so they should be on different instances.
I disagree. Grouping communities makes sense if they need the same admin policy. Admin policy sets a floor on what mods are required to police when it comes to things like hate speech and threats, but mods in a programming community aren’t going to allow that shit anyway, so admin policy is irrelevant.