There’s multiple comments about this now, so I’ll respond in general, Re: Shared home instance via launch parameter.
You now have to explicitly create instances rather than them just existing for any arbitrary name, but instances still continue to exist long after the last person leaves (for about a year!) - so you can keep your link running for quite a while even with no activity. Only when generating a new instance (e.g. for a new friend group) you will need to open it via the website first and copy the resulting link, once. Just make sure nobody hits “Close Instance”.
TL;DR: Current approach won’t even break, actually.
As for an official Group Home feature, we also think that’s a really neat idea, but it currently has a lower priority on our long to-do list.