Earlier quoted context omitted.
One possibility might be equal output for a given situation. For example, if a business increases profits then everyone who contributed should benefit. I'm not saying that a factory worker should make as much as the CEO, but they should both share in the reward since they shared in the work
And yet I’ve never heard the counter outcome being discussed. What do you do when the business goes on a down period and there’s just enough money to pay the employees but not the owner(s)? Assuming the employees don’t get let go (to have a simple example here), do the employees have to get a negative delta on their salary? If an owner’s pay is the true net post expenses, what if that net amount is $ < 0?
When the business goes up, the first thing that happens should be neither giving money to the owners nor giving money to the employees. It should be putting some money in the bank. The most salient reason for this is that just because the business is up this quarter (or over whatever short-term period is being considered) does not mean that is a stable increase.
Similarly, when the business goes down, the first thing that should happen is neither reducing the pay to employees nor reducing the pay to owners. It should be dipping into savings. That is, in fact, why the savings should be set up in the first place.
With this stated, it should become clearer what the answer to your question really is. Because neither employees nor owners should see an increase in pay until there are stable increases in business over multiple measurement periods, similarly they should not have to see a decrease unless there is a stable decrease in business. And if there is a sustained decrease in business, then there are likely other efforts going on to combat it, both in terms of cutting staff and in terms of finding out why the decrease has happened and trying to reverse it, so any decrease in compensation would not be happening in a vacuum.
The shorter statement that increases in business should result in employee wage increases is not (generally) meant to indicate that every temporary fluctuation in business should ripple to the employees, but rather that they should be given some of the long-term increase, as opposed to the owners getting the entirety of it and the employees getting nothing.