That used to be true in the past, but is no longer true with the release of the newest V3 app.
Since that app combined a number of Samsung‘s product lines, including their smart televisions and smart appliances, all into one app, they now no longer assume that customers have a hub or need a hub.
For example, someone could have one of their $6000 smart televisions and a bunch of LIFX Wi-Fi lights and want to create some scenes with those, and they can just use The new V3 app without ever having a hub at all.
Or the only thing the customer has is the Samsung robot vacuum. This is now the only app that works with that.
There are other similar fairly common integrations, but of course they can’t include the zigbee or Z wave devices which do need a hub. But as long as it’s an official integration, many Wi-Fi, Bluetooth, and cloud to cloud integrations work just fine with the new app without a hub.
This is a fairly recent change, and people are still getting used to it. 
Here is the official support-base article where they explain that you can add the smart appliances without having a hub:
https://support.smartthings.com/hc/en-us/articles/115002084986-Locations-in-the-SmartThings-app
You can create a Location and add compatible Samsung IoT devices without SmartThings Hub capability. (If you haven’t added a Location, adding your first device will automatically create a Location with the default name Home.) You can always add a SmartThings Hub (or compatible device with SmartThings Hub functionality) to the Location later
So it’s now a “hub optional“ platform, which it did not used to be.
SuperLAN Connect
There is one weird thing which I believe will eventually be considered a bug and get fixed, but right now doesn’t seem to be a priority.
There are some Wi-Fi devices which have an official integration but integrate at the LAN level using “super LAN connect.” These devices will tell you that you need a hub, even though you should be able to do it via a cloud to cloud integration. But because it’s the hub that monitors the local network for superLAN connect, they won’t let you add those without a hub. And even weirder, they seem to have included a few Bluetooth devices in that category, which really makes no sense. That’s all quite frustrating, and as I said, I hope they change that in the future.
I don’t think that’s what the OP has run into, I think instead they may have the issue I explain a couple of posts down where the WiFi has to be disconnected before it will let you change the settings. But I just wanted to mention it in case someone else finds this thread in the future.
The V3 app is still in a phase of rapid development and there’s a lot of changes every few weeks with it, and a lot of features which are still pretty glitchy. 