The company profiled, Central States Manufacturing, has compounded at 20% per year since its formation in 1988 (according to the article). In comparison, Amazon has compounded at 23% since its IPO in 1997. If you are lucky enough to be a worker at an employee owner company that has 1 in a million anomalous stock growth you will do very well. This is not surprising.
World wide public equities have grown at 5% real over the longest datasets available, 7% for US based companies. Even these numbers are misleading because company returns are heavily left skewed: a small minority of companies do tremendously well and the rest are stagnant or shrinking. From 1991 to 2020, 55% of US stocks underperformed 1 month T-bills. From 1926 to 2016, 4% of stocks have outperformed the total stock index.
I do not see what is so amazing about this? If you think that employees deserve a larger share of the spoils then you can advocate that they receive more of it directly as compensation, no employee owned corporation needed. If they will make the same on net but with some of it locked away in a single company's equity than you've just made those employees' economic situation _more_ precarious than it was before.
Non-employee equity ownership arises naturally but these articles always try to paint it as the result of the nefarious machinations of top-hat wearing capitalists. Suppose this company needs more capital than employees can raise but won't or can't take on new debt. Equity must be sold to outsiders.
The article also wrongly suggests that owning equity is exceptionally difficult without employee owned companies: "it's hard for most people to get ownership in something." But we have a whole public equities market that anyone can participate in and innovation has only made it easier over time. Index funds have made diversification automatic, fractional shares have solved daunting investment minimums and payment for order flow has eliminated transaction fees and concern about getting a fair fill price.