Spaces is just a directory of text rooms. Users don't just join every single room and rooms are independent from each other instead of having a single roles system shared between the whole server. In this model having an announcements channel wouldn't work since there will be people who didn't join the channel. Similarly people might not want to join a rules channel.

ATM people will see suggested rooms, auto joining is in the works.

However, don't see a problem. Why does it matter if they join each channel? you don't need to read a channel in Discord as well despite you are auto joined

>Why does it matter if they join each channel?

Higher friction to visit other channels means that it will mean less people will visit other channels. I've been in a Nix / NixOS room for a while and I had no clue I was in a space and that space had other rooms until you commented that it existed. I never had this issue with discord. It was obvious there were other channels the first time I used it.

> I've been in a Nix / NixOS room for a while and I had no clue I was in a space and that space had other rooms until you commented that it existed.

sounds like a temporary issue though: first only rooms existed, now Spaces exist, but the room directory still exposes rooms instead of Spaces