Focusing on the possible upsides tends to ignore the possible downsides. Worker ownership is only great when the company does well. If the company does not do well, the workers don't just lose their job but their nest egg at the same time. Let's not pretend that you can always influence whether your company will grow or not, sometimes you just work at Altavista and Google just launched.

The average worker has enough of their income tied up into one employer already, they don't need to have even more economic concentration. It would perhaps be better if every company was owned by everyone other than its employees, with the employees of every company being forcibly made to invest in every other company. That way everybody gets to have an cushion if they ever lose their job or their company goes under. A bit like a DIY UBI if you will.

It does, and Silicon Valley is built on that, but for startups it’s more of a lottery ticket, and for a tech giant, what you do as a worker doesn’t make much of a difference for financial results. And even in between, how the investment does is pretty risky and partly determined by unpredictable outside events, so you’ll want to hedge.

And then for shared ownership, governance is often messy.

Individual ownership of a stable asset that you can improve by making your own decisions (deciding what fixes to pay for, at least), is a different thing.