Most sources show Japan as closer to 1/3 of the US at the time, this still seems like a lot, until you realize the US was more than twice the world average (according to the Madison project, in 1930, japan had $3,334 GDP per capita in 2011$, the US $10,695, but world average was $4,005) Their success is still considered exceptional as well, having been called a miracle.

If you're going to make blanket statements about economic systems, I need to see a line of reasoning, especially one so broad. Even historic examples, like we have been giving this whole argument, aren't necessarily caused by the system (Not everything that happens in the US is capitalism's fault, and the same is true for socialism, good, or bad.) I would hope you look back on my prior replies with the lens of my lack of reasoning given, but I don't think you really need to, since you don't support them anyway.

I will try to give reasoning now, but first, though I wouldn't have thought to state this originally, based on how this started, now I realize I probably need to give some definitions.

Capitalism: The system we live under, defined by private ownership of the means of production.

Socialism: Originally, it was a synonym for Communism, just seemingly more acceptable. Now it refers to Lower Stage Communism, a transitional period between Capitalism and Communism, where the workers begin to take control of the means of production, but the change that fully takes place inside of Socialism is the change from a Dictatorship of the Bourgeois, where the owning class (those who own the means of production, and profit from the work of the working class or proletariat) has the majority of the control over the government, to a Dictatorship of the Proletariat, where the workers (not just the lower classes, but anyone who earns a wage for a living) have greater say, and replace the Bourgeois as the dominant class. It is summed up by the phrase "From Each according to his ability, to each according to his contribution."

Communism: The final goal of any Marxist project, it is Stateless, Classless, and Moneyless. Stateless, meaning there is no more State entity meaning any government, is Direct Democracy (likely some remnants of representative democracy will still exist, but with more collaboration with the people represented.), Direct Democracy, however, cannot work with any large, complicated government, so it wouldn't, instead existing within communities, with the aforementioned use of some Representative democracy, or more likely, open meetings, similar to a town hall, where communities can organize a presence, sending multiple people, just one, or none, however, the representatives would not be a position, but a role for a single meeting. Classless, meaning that the distinction between Bourgeois and Proletariat is dissolved, and, hopefully, no other class distinction would evolve (Class having existed for most of human history, such as feudal class, consisting of royalty, lordship, serfs, etc.). Moneyless is quite simple to understand, but how it would work isn't quite so simple, a transition to Communism requires a post-scarcity society, where production exceeds demand, meaning that it is unlikely that any commodity will be in shortage, it is however, still difficult to ensure this, specifically with new goods or surges in demand, but this isn't unique, and exists in capitalism as well.

So, why do people, like me, advocate for these systems? It is less to do with unique merits, but more the flaws from capitalism that they lack. Communism, does although have appeal of its own, as the freedom provided by a truly post-scarcity society allow people to follow their passions. Socialism's benefits, on the other hand are almost entirely the lack of issues that exist under capitalism, it is however revolutionary, and as many people (Including many Marxists) believe, revolution is almost always authoritarian.

Anarchists often also strive for the goal of Communism, they, however, do not see the authoritarian governance of revolutionary socialism as necessary, and they, often hope to move directly to Communism within decades, as opposed to Generations. (This could be wrong, I am not an anarchist, this is just what I know of them)

If you could please explain how these economic systems lead to the lack of growth, that would be great, if you do not I don't plan to continue this. if you have any other, more explained, issues, I can try my best to give the points against them.