You keep using the word "forced", but remember this is a voluntary system.
Either way, it's really, really dumb and inefficient. It just takes away people's freedom to pursue different employment and investment priorities in exchange for nothing at all.
I think you are taking too much of the capitalist system into account. Even though what I'm talking about may sound like joint stock corporations, there wouldn't be any actual 'shares' that you own and sell in a market.
It's not about investment, it's about ownership and voting rights.
What do you think the difference between investment and ownership is? Regardless, whatever it is, it has nothing whatsoever to do with employment. Why would anyone want a system that ties things together that have nothing to do with each other rather than obviously superior systems that allow them to pursue these things independently?
Say I want to work for company X. But I have no idea how that company should be run. But I might have great ideas about how company Y should be run and I'd prefer to have some ownership in company Y because that fits my investment priorities. For absolutely no rational reason whatsoever, your proposed system requires me to pick one company for these completely logically independent things. It just makes no sense at all.
And if they're not shares you own or sell, what happens when a person works for a company for a long time, builds that company up, and then stops working? They cannot sell their shares because they don't own them? So they just lose all claim over the value they added to the company? That doesn't seem logical or fair. It seems a system where the shares are owned and sold is much fairer.
In a hypothetical co-operative gold mine in a libertarian socialist community, if a new worker is hired by that co-operative, the worker is then entitled to vote in business decisions (or vote for a representative) and a share of the revenue to which the worker's labor contributed (on the terms voted on by the co-op, probably a proportional system). I do not see any reason why there would be any outside stock for investors in this system, it's not necessary and it goes against the ideals of self-ownership, economic democracy, and classless society.
The problem is, the worker may prefer to have a share in a completely different company because that company better reflects his *investment* priorities even though this company best reflects his *employment* priorities. There is no rational reason to advocate a system that prevents people from pursuing these interests independently.
This just stupidly hurts people for no benefit whatsoever. It makes absolutely no sense.
Why would anyone want a system that compels them into sub-optimal investment choices just to make optimal employment choices? Or sub-optimal employment choices just to make optimal investment choices? You are advocating a system that hurts people and gains *NOTHING*.
Say I'd really like to own part of company Z because it makes investment sense for me. But company Y is offering me a great job. Why would you advocate a system that forces me to make compromises? What is the benefit? It just seems like pure idiocy to me.