As Sagan said, “If you want to bake a cake from scratch, you must first invent the universe.”
We’re remixing everything all the time, nothing is completely new and that’s fine. We still move forward.
More specifically though — in the world of web development — some ideas are actually [as good as] original. When CSR/SPA became well established as an approach in web development, there wasn't a time before it when that approach had been common.
The approach to web development described in the article however is essentially the same approach that web developers commonly used 10-15 years ago.
n.b. I'm aware the CSR/SPA approach is more like 20 years old, but I'm making a judgement call on how common common is. Furthermore, when the CSR/SPA approach was first explored in ~2002, what old idea was it a new take on? Flash? If so, what begets Flash? There was a time before the Internet, and it wasn't all that long ago.