No argument there either, I do agree sometimes market monopolies need to be felt with though the bar is high in my opinion. If it were me I'd want to see proof of collusion, its easy for a market with only a few actors to independently make similar choices based on similar market incentives and data.
In this case though, it still seems like a more simple monopoly only with google. You don't need to consider other companies when the issue is related to the black box of search rankings.
I wouldn't personally want companies to be punished without evidence of collusion. A company isn't doing anything wrong by earning market share, and companies aren't doing anything wrong if they happen to move in a similar direction based on market incentives.
If we think free markets are generally going to move in the right direction, we should just want companies to want to fill market gap and outcompete. I don't agree we should make companies do anything though, at most governments should be tweaking incentives to attempt to push companies down a path without directly making them go there (even them I'm not sold that approach is worth it).
So there's no collusion or misbehavior, and the market ends up as a duopoly: one participant has 70% and another has 25%.
You don't think that alone distorts the market enough to merit intervention to encourage more competitors?
If you tie intervention to proven malfeasance, you allow abusers to skirt the rules for decades, entrench their positions with obscene profits, and then maybe eventually face consequences if they lose a legal case.
Instead of labeling some things illegal after the fact, monopoly and market law should be based around identifying some high market sharr situations as potentially dangerous and requiring compliance with additional regulations that make it harder for that dominant company to prevent competitors from starting and growing.
Otherwise, it invariably slides into state-aligned and -supported chaebols, because the government has incentive to ask large companies for help and they have incentive to cooperate with the government.
Yes, when crimes are committed it is often hard to prove and you won't catch them all. That's by design and a fundamental part of how our legal system was designed in the first place.
Having a duopoly as you described isn't in itself a crime, nor should it be. If they are skirting the rules such that they are breaking the rules, enforcement should step in as there is actually something to enforce. If the only "crime" is winning market share, what's the problem?
We've seen the legal gymnastics around market definition for monopoly purposes.
But it's harder for Google to make the case that it doesn't own at least a big chunk of {mobile OS} or {mobile app store} market share.
They can argue +/- a few percent over methods, but "We don't have a substantial market share" won't fly.