As @jkp mentioned, what they are doing is getting out of sales and support of home automation devices. But they will continue to offer the platform and the app. There are a couple of other companies, notably Tuya, which do something similar.
Here’s the official announcement thread you were asking about. The topic title is a clickable link.
I think the real significance is now that they have brought everything into one app, Samsung’s primary SmartThings client base in terms of both profit and numbers are people who have a “hub optional“ configuration. They don’t have a smartthings hub. They do have a smart Samsung appliance or television, and they may want to add some lights to that. Samsung wants them to have a nice looking app and to be able to do that.
If other companies find a successful business model in providing the hub and support for devices that require the hub, Samsung is happy to hand that part over. And one of the things they have to offer is access to the hundreds of millions of people who have those smart Samsung devices.
So from a business standpoint, I think it makes sense. The people in this forum may not be happy with some of the changes, but we are a very small percentage of the user base and probably have never been a profitable one.
Personally, I’m not happy with the lack of transparency about all the changes, but SmartThings has always made unannounced and undocumented changes, so that’s not unusual for them.