Just to play devils advocate - email isn't a great example. In the end, it's become a very centralized service. The protocols allow for decentralization, but these days a very large chunk of email ends up just being data movements in Google's databases and storage systems.

I could go on (the internet itself is moving largely to centralized servers in one of a handful of providers) but the point is - centralization seems to always win out. Can you name a handful of services which started out decentralized and by and large stayed that way? Here are ones which didnt:

Banking, stock trading, email, the internet (defined as computers connected together over tcp/ip), podcasting, blogging, music, gambling, video...

Centralization tends to enable scale, dispute resolution, trust, ability to change. There are downsides to it, but it seems they are easily outweighed according to customers and history.

I think the reason email is now more "centralized" (in the sense that most people use a few big providers like Gmail) is because most people just don't care about decentralization (at least for email). Not because the protocol wouldn't have scaled otherwise. Gmail works well and people aren't going to drop it just on principle.

Systems that started decentralized and remained so... BitTorrent I guess? I can't think of many, honestly. Most decentralized systems don't have a monetary incentive layer to keep people running it the way a blockchain does.

Yup, totally agree with the why. Many of the examples I gave don't have scaling issues per se. It's because people don't care and there are other benefits of central services. It's kind of the point though - the vast majority of people just don't find decentralization a strong value proposition.

Agreed. I'm under no illusion that most people are fine with the status quo. It's one of the reasons this stuff has not been very well received.