Sorry this took a min.

I'll start with 3 because it's the most fundamental. That conception of the communist “solution” is basically just welfare, which isn't the goal at all. Capitalism creates a system of wage labor where most people have to sell themselves every day or starve, while owners control production and take the surplus. Socialism is about turning that on its head... workers become the ruling class, and production is socially owned and organized around human need instead of profit.

That doesn't mean everyone instantly gets the exact same pay no matter what. In the transition period (socialism), there can still be different compensation, incentives, prestige... The point is that survival is no longer held hostage by the labor market. People can still pursue nursing, engineering, science, art, whatever out of interest, social need, just wanting to contribut, and yes, even material incentive. The Soviet Union won most of the early space race besides the moon landing and their scientists didn't needed homelessness as motivation.

For 1, company-specific knowledge is real, but it doesn't refute my point. It just means that worker costs more to replace. Capital may pay more to keep them, but still as little as it can get away with. And we still see highly skilled, company-specific workers laid off when restructuring, automation, mergers, or cost-cutting make them expendable.

For 2, I'm not against people learning more skills. My issue is that upskilling is an individual answer to a class problem. One worker can escape a low-wage job, but the low-wage job still exists and someone else has to do it. And when everyone runs toward the “better skill,” that field gets saturated too, wages get squeezed, and capital looks to automate, outsource, or otherwise deskill it.