I personally always enjoy Meta update posts on other instances to see what they're up to, how they handled a particular problem, or offer help if they need it, and welcome the same on the meta posts on my own community from non-members.

But that's just me.

because it affects the communities too, lots of outside accounts use the communities here

if there's downtime for the instance or database issues or something, then subscribers to c/programmer_humor or c/programming might want to know because it affects them too

People can use it to get updates on the instance itself, just because they don't have accounts here doesn't mean things on this instance do not effect them, such as planned outages or federation bugs.

Also since users from other servers who participate here are still part of this community, and may want to provide feedback in discussions related to the server or even provide suggestions for how to improve the programming.dev instance in general. I think locking other users out of the instance's meta communities is honestly bad practice and enforces tribalism in the Fediverse.

Instances aren't just servers that communities are hosted on, they are larger meta communities themselves, and people who participate in our communities also participate in our instance in general as if it were one larger community.