I have read some books. I recommend Cory Robin as an author, he manages to be fairly entertaining. You also don't think maybe you are applying a slippery slope fallacy to socialism? Systems can be considered "complete" by the people experiencing them at any level of socialism. Generally speaking Communism isn't even very popular in very socialist countries.

Communism being adjacent to facism in the ring model of visualization is largely due to the fact it hasn't been successfully implemented and in being unstable eventually tips into a different form of autocratic format. I don't particularly subscribe to that visualization model personally. It's far more common on the right who has been conditioned to look at communism and facism as being natural progressions of each other.

And no. Socialism is not always in strict opposition to capitalism. None of this is that simple. It doesn't always front worker ownership of means of production either. Those are both socialist ideas yes in the same way Halloween and Friday the 13th are both horror genre. They represent only a fraction of many different presentations of socialism.

I wish I could give a simple overarching definition of socialism for you but quite frankly it's really hard to give a simple description of socialism that actually encapsulates all of Socialism.It is kind broadly divisible into market, non-market Socialism and Social Democracy as long as you're willing to ignore some of the more difficult to pin down stuff...

Market socialism is the chunk that really doesn't jive with your strict socialism / capitalism dichotomy. As a economic theory it both functions INSIDE the framework of capitalism existing as a given but is also anti-capitalist as far as it seeks to limit how capital can be invested or extracted. Non-market socialism looks for allocation of resources in ways outside of the idea of contemporary market systems.

Then there's Social Democratic Socialism - the branch of socialism we think of as social justice...it does kind of factor in money and economics tangentially because it is concerned with precarity of underprivileged classes but it more concens itself with ideas of equality in more of the sense people think of when they hear the words "woke". Disabling social hierarchies that value certain people over others.

There are a bunch of different disparate socialist ideas that intersect with virtually everything. The environment, government service, transit, models of economic systems, unionization, city design, public services, taxation structures... And while you can sort of aggregate different any particular socialist party into rough clusters around specific manifestations of socialism you can have very different manifestations which are still "socialist".

Historically one could blame this all on basically being a counterculture situation. When you dig up the thinkers behind libralism or conservatism you get your John Locke and your Edmund Burke. The writers that followed were more about hammering out the details. These people created fairly basic ideas. Basic because they were very European centric, narrow and were enforced on others in the form of colonization. They compressed everything into a simple straightforward philosophy that if you fell outside of somehow you basically earned your misery.

Socialism grew up in the shadows between liberalism and communism. Between the occupying force of liberalism which always had built in exceptions to the freedoms it promised and the Communist /anarchist idea of violent resistance. Socialism had so many writers in it's early days positing middle ground situations between those two extremes that it was always kind of a schizophrenic mood board ... But critically when you look at the early socialist writers a lot of them weren't trying to upset the capitalist applecart overly much. Some of them were even capitalists themselves.

And socialism keeps getting bigger. More and more thought into dissolution of the Eurocentric and traditional norms means you have feminist socialism, Indigenous Socialism, Black Socialism, Disability Advocates, Gender and sexuallity focused socialism, anti-kyriarchists... Marx and Lenin would be completely out of their depth trying to tackle it.

You are dipping your tin cup in a lake of socialism holding it to your chest and saying "all that exists of socialism is held in this cup" ignoring the fact there's a whole god damn lake you could swim in.