The debate at the time was whether a business of a certain large size or that met certain criteria was a de-facto anti-trust violation or if it had to also eng

The debate at the time was whether a business of a certain large size or that met certain criteria was a de-facto anti-trust violation or if it had to also engage in price-fixing and other monopoly behaviors. The court decided that it had to engage in direct monopoly behavior. Rightly or wrongly this is what allows a market with 2-3 players who own 90+% of all sales to function as an effective monopoly trust. It's a prisoners dilemma and all know there is nothing to be gained by actually competing - so they don't meaningfully do so (or put out a few fig leaves to pretend to compete). Because they never actually conclude an agreement to fix prices they aren't doing anything illegal. You could interpret the law such that a de-facto monopoly was illegal but that definitely has a lot of problems of its own. I'm not sure where I come down on this issue. Having everything dominated by huge corporations is bad for society overall, but it does provide a lot of opportunity for startups to disrupt things. Unfortunately money (thus power) is so concentrated we are increasingly seeing the legacy players turn to campaign contributions and political games to snuff out competition. Yet some amount of regulation is far preferable to the alternative. Definitely difficult to strike a good balance.