With Snapchat adding this feature, you now have the layer of your friends (what they are sharing publicly and what you are taking together privately), media brands (discover), and the entertaining personal content from the global and regional community (TikTok).
I was asked questions on live TV about why are social media apps replicating each other. I have been asked this question a lot each time an app adds a feature. It’s just that they all want people to stay with them, not go spend time on another app and so when they see something people like, they try to add it and put their spin on it. It’s like when two restaurants are competing. One realizes what’s the best-selling dish of the other, and they will try to replicate it with a twist to gain more customers.
What you need to also remember is that there are billions of people on the planet. No app can have them all but adding features ensures that whatever portion of people a single app has, it will be able to keep.
Finally, if you still disapprove of what Snapchat did, think hard and try to remember which app had stories and photo filters before them all.