Can you explain the dream suite? I've never played Animal Crossing before New Horizons?
In the dream suite, you can input someone's ID code and "visit" their island (walk around it, interact with villagers, tour their houses, etc.) without the other person having to be online. While "dreaming" you can't do any harm or have any permanent effect on the person's island you're visiting. So, you can have many people come view your town without any risk of them plucking flowers, stealing fruit, your villagers talking about them later, etc.
Also, they can only dream about the version of your island you saved/submitted with the character who runs the dream suite. So you could submit your town in spring when the cherry blossoms were blooming, or when the fall leaves were out, or during a specific time of day/night to give your town a specific mood, and dream visitors would only be able to see that version of your town until you re-submitted it with a different version. This allows you to craft specific scenes or maintain a desired atmosphere. Check out Aika Village for an example of how they used a night-time save and specific time of year to create a particular mood.
In New Leaf, people set up absolutely AMAZING towns to tour - look some up on Youtube if you're curious!
EDIT: As for me, I would LOVE the dream suite to return, and I hope it comes back soon! I adore touring other people's islands, but I always feel a bit self conscious asking strangers if I can come over and take a look/wander around. I loved the dream suite in NL because I could really admire people's creativity from afar, and visit towns made by people all over the world. I currently have no chance of visiting many islands because you can only really get dodo codes easily from other people who speak the same language(s) as you.