I sorta disagree in the context of having a middle class. We did and still do have our oligarchs, we had our Gilded Age which I would definitely call an oligarchy that lasted into the early 1900s with the Rail, Steel, and Oil barons to name a few. But the middle class exploded in the post-war years, unions became powerful, corporations and the rich were brought somewhat to heel with consumer and worker protections, along with high taxes that kept the rich from taking an even bigger chunk of the pie. Yeah, the rich still did rich people stuff, but they tended to do it more on the DL.

Now? We’re literally at the point where people are so absurdly rich they can have private space programs, dump hundreds of thousands into political campaigns, crush unions, invite themselves into the government, and have fuck you money. Literally, Musk telling people to fuck themselves.

So IMO yeah, the US is an full-on oligarchy again after a brief semi-respite in the middle to later parts of the 20th century, and it’s a shameless and open one.