Your argument seems to be akin to "History shows that every tyrant who ever existed has died." Yes but if one or more new tyrants has been born for every one that died, what consolation is it? Different corporate overlords isn't the same as no corporate overlords.
Go back to the pre-industrial era, and you own essentially nothing unless you're royalty. Move forward into the mid-19th century and the picture has changed - bankers and railroad barons have grown powerful enough to assert some control over governments. By the 20th century you have a whole array of public services(water/phone/gas/electric). And today, the big discussions are mostly over information businesses.
Example: Even though Apple, Amazon and Netflix have done a lot to usurp the nature of retail and media publishing and can be seen as "tyrants" of their respective markets, they've given up control in other ways; you have considerable freedom to publish and distribute products through their services. They still curate, but not extensively. And, on balance, they offer a better profit/consumer value ratio.
The overall picture adds up to something more complicated than "new tyrants, same as the old" - the quest for profit is increasingly causing them to battle each other, as they keep stepping on each other's toes, and that's forcing a kind of competition that was unimaginable in previous eras. It's still imperfect because some elements of the system will occasionally try to take the rest hostage(e.g. banking, recently), but some amazing things are happening regardless - Twitter revolutions, anyone?
Well, a free enterprise system is just that: one in which consumers have choices. The fact that Google dominates search, or that Apple dominates mobile devices, or that Microsoft dominates desktop computing hardly limits my "freedom" in any real sense of that word and, in the meantime, I will gladly use Google over AltaVista, Apple over a Brand X music player, and Microsoft over WordStar for the benefits I derive from those offerings. In other words, I don't have a problem with a company making proprietary offerings if such offerings give me better value than what otherwise exists and, if I don't like them, I don't have to deal with them.
So, I feel I have my freedom today, just as I did years ago when IBM dominated enterprise computing, and that is why I am (as I said above) quite relaxed about the idea that private corporate interests can control and dominate their respective fields of activity. So long as no government entrenches them permanently as monopolies no matter what their virtues, the activities of Google, Apple, Facebook, etc. are entirely consistent with a free system of economic activity.
If you would abolish the idea of market-leading companies in a free enterprise system, what would you replace that with? In other words, how are you using the word "freedom" and "tyrant" in this context? These are genuine questions because, apart from your use of the term "tyrant" for rhetorical effect, I don't understand where you are going with this idea.
But I think that one can articulate the problem of abusive monopolies as being narrower than simply companies leading the market.
The distinction between rent-seekers and profit-seekers is rough but it's a little closer to the original complaint. We can define abusive monopolies as companies which have acquired not just a strong position in the market but also a legal or force-based cudgel to drive off all serious competitors. Telcos having a monopoly on civic rights-of-way is an example of this. Companies using software patents to scare-away competitor are another example of this.
One problem in dealing with this situation is that in a fair, "commodity" market, margins tend to become "paper thin". Thus there's a lot of capital out there chasing opportunities to get a choke-hold on one or another markets. I don't have any idea what to do about that.
> The fact that Google dominates search, or that Apple dominates mobile
> devices, or that Microsoft dominates desktop computing hardly limits my
> "freedom" in any real sense of that word
Limiting freedom doesn't apply solely to the freedom to make a choice, it also applies to limiting the options one has to choose between. When AT&T lobbies the government to allow them to refuse access to their last-mile lines to 3rd-party ISPs, then AT&T is limiting my freedom b/c now I have fewer choices in ISPs in my area.
Freedom means you do what you like with things you own. It does not mean every market should (or will) organize itself so as to maximally benefit you.
As for AT&T: of course. Behind every good monopoly is the government (and then they're protected by law -- and the threats of murder, blackmail and kidnapping for violation).