I don't really agree with this perspective. I'm not a big fan of the giant tech companies, but I don't think they were directly responsible for the centralisation of the internet.
In my view, the centralisation of the internet had too major causes: spam; and the fact that creators are drawn to audiences, and only rarely the other way around.
The hard truth is that there is no decentralised solution to spam. If you allow other people to post comments or content to your site, you will get inundated with spam. Only the large tech companies have managed to reduce the problem to manageable levels.
The other factor pushing centralisation is that creators are drawn to audiences, and not vice versa.
One of the blogs I follow is Arnold Kling's Askblog. It's a nice blog on economics and politics with a lot of good commenters. Indeed, most of his posts get between 10 and 30 comments of high quality, which is quite excellent. In some ways, it's the "beau ideal" of blogs that the Hacker News people were mourning.
Yet last year, Mr. Kling started posting essays on Medium.com instead of his own site. His reasoning was basically that he wanted a larger audience.
The lesson here is that creators go where the audience is. If everyone watches videos on Youtube, then creators will make videos on Youtube.
I think that between spam and audiences, it was inevitable that the internet would centralise. A de facto carrot and the stick, one which the tech giants took advantage of.