They can split these companies up but eventually some piece/s will gobble up the rest through dark mergers and aggressive business dealings and become bigger than their predecessor.
There are plenty of gigantic corporations who are probably looking forward to eventually acquiring parts of Google. I wouldn't put it past Verizon, who has not only partnered with Google but also fought for telecom control against them. Don't we also need to break these companies up as well? Or do they have too much influence in the government? Ajit Pai, for example, famously worked for Verizon before government.
I'm not trying to protect Google. But I just think that the government needs to find a way to enforce these breakups more evenly or else it just leads to further consolidation, as you pointed out.
Pai worked at Verizon for two years between 2001 and 2003. He was appointed as FCC member in 2012. How much loyalty do you have to a job you held for two years, nine years ago?
But you shouldn't be so sure that it has had zero influence, either.
I think we need a better solution than breaking up monopolies. Perhaps something like caps on profit margins and/or asset taxes that apply to companies which carry too much market share.
The main obvious cuts for Google and Amazon are to fully split up the technical infrastructure and Web hosting technologies from the consumer marketplaces. For Google, they would force Alphabet to spin off Google Cloud along with Google's own datacenters into a new datacenter host, and force Google/Alphabet to purchase hosting services at arms' length. Similarly, Amazon would be forced to be fully at arms' length with AWS.
As an aside, Facebook could not be directly split up in this direction, but instead regulators would probably choose to unwind their M&A spree of the past decade, in particular spinning off Instagram and WhatsApp.
Your question now can be reframed: What stops Alphabet from becoming big anyway? Nothing, really, aside from the same regulators that have the responsibility of splitting them up right now. Nothing short of legislative action will work, after a certain point.
Edit: instead of downvoting me, you may want to argue why AT&T is any different than Amtrak, The Postal Service, and the TSA.
It isn't. But that's not an argument for nationalizing AT&T; it's an argument for privatizing the others. In fact, two out of three of them already have private competitors in the US; the only one that doesn't is Amtrak.
[1] https://www.fool.com/investing/general/2013/03/04/how-the-po...
So what? That has nothing to do with the fact that private companies have proven, through the entire history of the United States (including before the USA was even an independent country), that they can provide postal service. So there is no need for the government to be doing it.
> as for the TSA, it used to be private, do I really have to argue why that was a bad idea?
If you have such an argument, you should make it to the airports that use private screeners today.
Um, what? Rent seeking is one way of taking advantage of government-granted privileges. How are FedEx, UPS, DHL, etc. rent seeking?
Sure!