Sure we should be trying to halt it! How? That's tough. We've got economies of scale and the network effect working against us. But there's a lot going on in a lot of places trying to address this. I'm no expert, but it's a topic of great interest at the Berkman Center (where I'm a senior researcher), e.g. AmberLink.org and Perma.cc. Tim Berners-Lee has the Solid project (http://www.csail.mit.edu/solid_mastercard_gift). BitCoin and especially the BlockChain tech underneath it offer some hope. The W3C WebID (https://www.w3.org/wiki/WebID) initiative could help decentralize authentication. There's no shortage of projects underway. But the forces of centralization are well-entrenched, powerful, and often offer great user experiences.

I share your less than optimistic fears. But one of the hopeful things about the Net is that large centralized players can co-exist with decentralized sites and services. The long tail does not get the attention that the short head does (by its very nature), but there will always (?) be lots of creative work and lots of meaningful connections being made there.

Not sure it can be.

The old systems where decentralized and used defined protocols by necessity.

This because you needed software at either end that understood each other over said protocol.

With higher bandwidth, more reliable connections, and the web, the protocols have become fluid, as one end is downloaded and updated each time someone types a url into a web browser.

In a sense we are back at the leased terminal era, only with prettier graphics.

I no longer fire up a usenet client, i go to reddit.com.

I no longer fire up a IRC client, i go to slack.com.