> Government fiat generally makes problems worse because the government is a monopoly

That's one problem, yes, but not the only one. Good government is a public good, and elementary economics tells us that public goods are underproduced. Or, to put it another way, concentrated special interests have a larger incentive and more concentrated resources to corrupt government, than dispersed individuals have to keep it from being corrupted.

Also, governments aren't quite monopolies as long as people have the right of exit--if you don't like your state's government, you can move to another state, and if you don't like your country's government, you can move to another country. Granted, the transaction costs for such moves are high (particularly for the latter), but many people still do it. That exerts at least some competitive pressure.

> a monopoly/cartel isn't a competitive market

It depends on why it's a monopoly. If it's a monopoly because of special privileges granted by the government (which most monopolies are and have been historically), then yes, it's not exposed to competitive pressure. But if it's a monopoly because it provides better quality and lower prices for its products than any competitors, then it is exposed to competitive pressure--and it's succeeding at dealing with it. That's not a monopoly; that's a win for the free market.

The real problem with a company like Google is that its users are not its customers, so the whole idea of "competitive pressure" in the usual economic sense doesn't even apply. Google has no incentive to provide products that benefit its users, other than the fact that it needs a critical mass of users to be attractive to its actual customers (advertisers and other companies to which it sells data and access to users' eyeballs). What's more, since Google's users do not pay for its products and services, Google has no idea how valuable those products actually are to users, since it has cut off the best source of feedback--what users will pay for.

> the market can fix any damage by transitioning to smaller suppliers not subject to antitrust rules, which is the thing that actually solves the problem

That only solves the problem if the problem is that the smaller suppliers can provide better quality and lower prices to customers. But that's not even the problem with Google; see above. Google's actual customers don't want smaller suppliers, because Google's value to them is precisely its size. Breaking up Google without changing the basic business model would just create huge incentives for its customers to game the system, getting pretty much the same things they are getting now, but just with more maneuvering under the table.

If the government is going to do something hamfisted at all, the obvious thing to do would be to outlaw the ad-supported business model altogether. Make Google, and Facebook, and every other such platform, charge users a fair price for the services they provide, and let users, in a free, competitive market, decide what services are worth their cost. But of course that would be politically insane, because the users themselves don't want to pay for those services; why should they, when they've been conditioned to have them for free for so long? Only weird outliers like me would actually applaud such a move; I'd be happy to pay Google some reasonable fee per month to use search and maps (which are the only Google apps I use) if in exchange my data was no longer sold to third parties. But it doesn't seem to me that most people would agree with that.

Another suggestion I've seen is for the government to force Google, and Facebook, and every other such platform, to open up the APIs for all their services, so anyone could write their own client. That would enable clients to be written that didn't show ads and didn't do all the other tracking that Google's and Facebook's own clients do. But if Google and Facebook are still stuck on the ad-supported business model, again, that just creates huge incentives for them to game the system, creating new hidden back channels for their actual customers to get the data they need while pretending to have a free, open, public API that any client can use. Clients can only hide so much; at the end of the day they still have to make requests to the API, and those requests contain the basic data that the platforms are selling.

> The worst thing they can do is fail to do enough damage to the incumbents to restore competition

No, that's nowhere near the worst case. The worst case is something like locking down the entire Internet, so, for example, a site like this one can no longer even exist.