It is not clear the benefit is greater than increasing wages, but that's another thing.
But if everyone does this, to the point that there are not enough potential consumers for the majority of products, then there is no benefit to lowering wages. You can't sell anything to anyone.
In the end, no one wins the race to the bottom.
The answer to the question lies in what is missing from the equation: the existence of stockholders. They are potential customers too. You don't need to sell everything to just employees, that means you can underpay them and still be sustainable as long as stockholders buy things too.
But there are limits to how many things a customer wants to buy. Once the stockholders' needs are satiated, the rest of the profit won't be spent. At that point, in order for businesses to be sustainable, this balance has to be redistributed as increase in wages.
I have to say, though, paying my employees more so that my competitors have to pay their employees more so that their employees will buy more stuff from me sounds like a pretty dubious business strategy. And one that certainly won't work at all if there's enough of a labor surplus, because my competitors can keep their wages low and still find employees even if I'm paying an order of magnitude more.
Consumers are largely employees of businesses. If consumers do not have money to buy things from businesses then everyone loses. Instead of engaging on a senseless endeavor to lower wages as much as possible, strive for a FAIR wage that will allow consumers to do business with businesses.
If all of your revenue is from sales to your own employees, fueled by the wages that you're paying them, then your business is, by definition, not incurring a profit.
Maybe that's fine if you're like a farming coop or something, but it certainly isn't going to get anyone to invest in your enterprise.