Err, Bork was advocating for his view, so i'm not sure he's a good source?

Look, your argument amounts to:

For 60+ years, between 1920 and 1982, there was literally no legal theory development in antitrust. No other cases, no thoughts by anyone, no articles. Then suddenly, Bork came on the scene and redefined everything overnight!

Certainly that would have made my antitrust law classes a lot shorter, but i don't think it's reality :)

Let me try a different source for you

Here's what one of the authors of the act (Senator Hoar) had to say about it: ""... [a person] who merely by superior skill and intelligence...got the whole business because nobody could do it as well as he could was not a monopolist..(but was if) it involved something like the use of means which made it impossible for other persons to engage in fair competition.""

Oh look, a consumer welfare argument.

Also, here's another case from the supreme court in 1940 (Apex Hosiery Co. v. Leader 310 U. S. 469) "The goal [of the sherman act] was to prevent restraints of free competition in business and commercial transactions which tended to restrict production, raise prices, or otherwise control the market to the detriment of purchasers or consumers of goods and services, all of which had come to be regarded as a special form of public injury."

(emph mine). A very clear consumer welfare argument. They also cite supreme court cases.