It wouldn't impact the sale of a business but it would impact their expected return on the business in the future. Given the tax proposals that were on the table, they would have expected less income.
I hold a private corporation with my wife. Before I joined the chamber of commerce just a year and a half ago, I earned income and I used the tax laws as they exist to minimize my income. As you say, a private business would do that. An individual would try to minimize their tax, I suppose, as well. I certainly tried to do that. Knowing my specific example and the measly amount of money that I earned, I know that I would have.... I took dividend income. Taking dividend income and sharing it with my wife, who invested in my business, allowed me to pay less tax, which I then reinvested in the business.
At that point, I was a part of the middle class and I was getting a little bit more income by utilizing the tax codes as they existed. That would have changed, given the change.