We used to have this. Then GMail took over email, Facebook took over most people's communication, reddit replaced usenet and so on. We let the general masses sleepwalk into corporate data silos.
Reddit is mostly publicly accessible, and run like some kind of low-profit community-directed social benefit corporation. But... It is increasingly infiltrated by marketing in subtle and frustrating ways. Maybe this is why it exists.
Facebook, however, is just a nightmare. It gives us one thing we lacked before, which is a centralized identity service, and using that as leverage twists everyone's arm into joining and directing all communication through it. I can use any email server and talk with my friend on gmail. I can browse reddit anonymously. But facebook won't be satisfied until it owns my digital soul.
We need tools. They will have companies behind them. So, we can't throw everything away. But, can we draw the line at the walled garden of Facebook? It is a bridge too far. It is the end of the internet. Please, don't give in. Write your friends. Call your mother. Email your baby photos. Post your videos where you get credit (even revenue!) for them. Remember that ten thousand years of humans went to parties, got laid, and had your ancestors without an event page that required a signup and login.
1) Hostile use of e-mail has increased at a rate higher than exponential, to the point where spam prevention is an incredible chore, and the things that make it to your spam folder on Gmail isn't the whole of it, particularly if you aren't cautious in how your e-mail address is used. 2) People no longer have just one computer. They have a work computer, a home computer, a smartphone... and they routinely change those devices.
Gmail solves those problems. Gmail takes care of all kinds of spam prevention and other infrastructure tasks. You can access it from almost any computing device you have. And it does so nearly painlessly. You don't have to delete e-mails on your remote server because you're running out of space. You don't have to sync anything. There's no configuration. There's no cost. Can you get most of the way to a solution as nice as Gmail on your own? Yeah. But it's not as low-effort or low-cost, and I think people underestimate the expense, difficulty, or shortfalls of the best non-Gmail options for personal use, especially for people who are not either professionals or hobbyists when it comes to using computers.
The general masses didn't sleepwalk into corporate data silos. They went there because the open Internet is a shitshow. It is filled with incredibly dedicated and hostile people who want to run scams, spread malware, do DoSes and all sorts of intentionally hostile things. It is also filled with a lot of more innocent hostility -- nominally compatible software that in practice has weird corner cases, bad documentation, bugs, and so on and so forth. And decentralization is a real hard problem in software. Look at Aphyr and Jepsen. Look at IRC and its interminable netsplits. What you call "corporate data silos" are things that managed to solve problems people really have. Those solutions, yes, have other harms. But people didn't make bad choices or wrong choices, they made entirely sensible choices based on a different set of wants, resources and priorities than the typical commenter at Hacker News. That doesn't make them dumb or "sleepwalking," and condescending about real people with real needs is not going to solve anyone's problems.
The thing about gmail is not its services as a email server, but that you basically have to use Google's site or apps to access the email.
Yes, there is imap support. But as best i understand it, the implementation is "idiosyncratic" to put it mildly.
Similarly, Google used to run a IM service using XMPP. But then they killed the federation feature (allowing other XMPP services to communicate with Google's users), and then phased the whole service out for Hangouts.
Facebook also used XMPP for their IM service, but has since also disabled it.
Thing is that as long as they were using XMPP, i could have Pidgin sitting in the corner and keep up with friends and family on either service. Now it have to run 2-3 apps (and non of them are available for desktop Linux) to do the same.
While it may not be a sleepwalk, it sure edges close to "bait and switch".
Facebook's real name policy is one way to stop that. Google's "one account for all of Google" is another, because it takes effort to maintain a convincing fake account. OpenID tied to cell phone numbers might work; the cell phone numbers don't have to be disclosed to the sites using the ID for signon. While you can buy multiple cell phone numbers, they're not free. So a solution to that problem might be possible.
It's hard to monetize federated systems. Note that YC doesn't fund any. A few exist; there's Friendica and Diaspora, and, of course, the remnants of USENET. They seem to have a few thousand users total. It's not a technical problem.
The truly heroic will find ways to make what's "best" also the cheapest and easiest solution. But who wants to undertake that herculean task without being very well compensated for their effort? And there's the rub.