You should read a book called "designing data intensive applications" to fully grasp what you are suggesting. But the answer is that what you are suggesting is

You should read a book called "designing data intensive applications" to fully grasp what you are suggesting. But the answer is that what you are suggesting is not simple, cheap, or easy. Quite the opposite. The book also uses Twitter's architecture for many of its examples, and you'll quickly see that something like even just building a user feed for millions of people is rather complex.