the idea that history is going somewhere, that is has an arc, is an old idea
the consequence of this idea is a view that some cultures are evolving and other cultures are devolving
that some cultures are more advanced, and therefore have more right to steer civilization
They used to say that if your nation had colleges, and rule of law, and you had art that was full of heady symbols, and you treated women with the proper respect*... then you had civilization. And if not, then your culture is still stuck in the past, and we're actually doing you a favor by colonizing and bringing in a bunch of Nabobs to set up shop.
And everybody bought into this for hundreds and hundreds of years.
After World War II, much of the world was absolutely devastated. Philosophers everywhere asked "why did this happen?" and one common conclusion was that Nazis really bought into this myth of "progress". That modernist thought distilled their version of Nationalism. Their superior national identity (clearly superior because of good breeding and art and public works) is what they thought gave them the right to do everything they did.
And in the shocked wake of the holocaust, in the desolation of europe, postmodernism was born. It was, at its core, a rejection of this "history has a grand arc" idea.
Now that all the WWII vets are gone, we're seeing these ideas return. Nationalism isn't a scary word anymore, people are openly identifying as nationalists again. It is no coincidence that these "nationalists" are the same people opposed to Black Lives Matter, the same people running the Trump government. Trump always talks about how the people sneaking into the US are coming from "shithole countries"... at his core, he really believes this, that some countries are better than others.
None of this denies that certain forms of advancement exist. Computers get faster over time, right? nobody's saying an Apple ][ is the same thing as a modern laptop. What V3x is saying is that civilizations don't advance in the same way computer technology advances. You shouldn't think of cultures (especially our own) as having a "progress meter" which naturally fills up over time.