It's not just the way they are written, it's also the way they are interpreted. Antitrust used to have a lot more teeth pre-Bork, among other things, because it was much more proactive in terms of anticipating negative effects on the market even before the company would become a glaringly obvious monopoly.

Here's a case from 1962: https://supreme.justia.com/cases/federal/us/370/294/. Note in particular the basis under which it was determined that the company in question is in a market-dominant position.