It was initially used as a response to Boomer advice and arguments that are outdated. “When I was 22, we bought our first house, I didn’t live with my parents. I worked to pay for college and I didn’t need to rely on student loans. I walked straight into the manager’s office, looked him in the eye and asked for a job. Kids these days are so entitled and lazy.”
None of this is realistic today. And if you try to explain why these things don’t work anymore, you get shot down because it’s just a problem with your generation. “OK, Boomer” came as a response to all of this.
Has it jumped the shark? Yes, absolutely. But it came as a response to the Baby Boomer generation not listening to modern days struggles young people have. No it’s turned into a response for everything.