The problem is that when the market is already consolidated, you need one to get the other.
Suppose you want to compete with the major phone platforms. Your biggest problem is apps. No apps, no users; no users, no app developers.
A way to fix this is to create a cross-platform app development framework. Developers would love that -- write your app once and it runs on both the existing major platforms and any new ones? Great!
Except that the incumbents block it. You can't create a competing app store for the existing platforms, which means you can't leverage that into a competing platform.
But without competition there, they can also do this:
https://news.ycombinator.com/item?id=24304275
So there goes your competition for Twitter and Facebook.
Constrain them from limiting competing app stores. Works a lot better than doing nothing.
It seems there are perhaps three(?) options that come up:
1) Constrain big tech via regulation (thereby in some sense transferring the power to regulators/government, with the hope that it would in turn be influenced by democratic processes)
2) Or, directly influence big tech behaviour through boycotts and other consumer action.
3) Or, break up big tech forcibly or again through consumer action to switch to alternatives, thereby diffusing this power.
And you prefer 3. I think I do too.