As if those countries had anything reasonable.

Why don't you look to Europe instead?

Russia is literally capitalist though????

This is true. Russia is in fact a good case study of late-stage capitalism. You see, in American capitalism, everyone started equally and then had to build up to their monopoly positions today. In Russia, some people just started out with monopoly positions, due to corruption. So if we want to see what happens due to monopoly positions, we can just look there.

Americans all started equally? You sure, that the early comers, to america, who got huge amounts of land and resources started equally to irish and itallian immigrants?

And even the modern monopolies... Gates and his mom getting him a deal with IBM is a bit different than someone else without a well connected mom.

And looking at tax rates companies like facebook pay, I think corruption is very well alive in USA too.

Started equally, quickly became unequal, but nowhere near as quickly as Russia, which started at maximum inequality.

There is a middle ground.

“As a policy regime, it is described by academics as advocating economic and social interventions to promote social justice within the framework of a liberal-democratic polity and a capitalist-oriented mixed economy.”

Some of the world’s most successful countries are run that way.

It is called social democracy.

I'd like to think there are a wider group of options than a binary choice between "American Late-Stage Capitalism" and "Venezuela"

I'm sorry to have to break it to you but Venezuela and Iran are capitalist countries.

Perhaps when make a similar comment in future you could expand a bit and sketch out a possible alternative to that of people being free to to trade things of value with other people under the aegis of a dynamic regulatory system? I guess you mean a specific meaning of 'capitalism' but the nature of that is not clear at all.

Consider:

Option 1: the definition of "capitalism" requires that zero regulation be applied. In that case, abandon "capitalism" and replace it with whatever you'd call the same model but with regulation.

Option 2: a significant amount of regulation actually is enough alone to fatally destabilize capitalism. I do not believe this to be the case, but if it were, then it should very likely be abandoned, but it's difficult to know how other options might behave in this hypothetical universe.

I would argue that capitalism is exactly what the American system is. These terms are descriptive rather than prescriptive.

That's certainly a model one could use, but it strikes me as not particularly useful.

Claiming lofty ideology is not useful because those policies never exist in real life

Increased precision in base concepts makes it easier to measure and reason about the real-world drift from those bases.

That's assuming that those bases are even the goal for the people implementing the policies, which I am not convinced is the case in the US.

If that is not the assumption then we can just make arbitrary claims about anything and calculate "drift"

I'm looking at this from an economics study view, not a public policy view.

Definitions have an inherently arbitrary component, sure. But stable, precise definitions are far easier to reason with than a shifting definition like "whatever the US is doing right now".

The study of economics is not exactly known for its rigor, I'm not sure how much value that has

Gotta start somewhere.

Do you think capitalism can exist without policy and regulation?

People being free to trade things of value is not capitalism. Many other economic systems allow for this.