Compulsory profit-sharing seems like it might have some unexpected downstream effects. I think we already see some fairly creative book-keeping in industries where there's utility in reducing your company's apparent profit. The loopholes are many and the regulatory burden of identifying and closing them all is significant.

And there's no guarantee my base pay would stay the same if profit-sharing become the law of the land-- it doesn't seem improbable that my base might decrease in this new economic landscape. Suddenly, part of my income waxes and wanes according to strategic decisions that I don't get to play a part in, according to market forces that I can't fully predict. My life overall becomes more volatile.

I'm not against voluntary profit-sharing. The company I work for now does it, after <x> number of years of employment. I just suspect a blanket mandate would come with some baggage.