Last year Jillian York, a free expression activist, was temporarily booted off Facebook for sharing partially nude images. The offending photos were part of a German breast cancer awareness campaign which featured, well, breasts. Facebook flagged the post as a violation of its Community Standards, which strictly prohibits most types of female nudity. Though the account suspension lasted only 24 hours, it had a powerful impact on York’s ability to get things done.

WIRED OPINION ABOUT Chelsea Barabas (@chels_bar) is a research scientist at the MIT Media Lab and former head of social innovation for the Digital Currency Initiative. Neha Narula (@neha) directs the Digital Currency Initiative at the MIT Media Lab. Ethan Zuckerman (@ethanz) is the director of the Center for Civic Media at MIT and associate professor of the practice at the MIT Media Lab.

Locked out of Facebook, York was unable to complete her work or post comments on news sites that use Facebook’s commenting tools. And without Facebook credentials, York could not access apps like Spotify and Tinder. Tick off Facebook and you may be unable to work, date, or listen to music. York’s suspension highlights the ever-expanding ways in which we now rely on large private platforms to facilitate our online activities.

Over the last 13 years, Facebook has evolved from a lifestyle site for college kids into a cornerstone of civic life. It is one of a handful of very large platforms that dominate our online world. As such platforms have gained traction, the web has transformed from an open space for free expression into a corporate-owned gated community of private platforms.

The power of giant platforms like Facebook, Google, and Twitter leads to problems ranging from the threat of government-ordered censorship to more subtle, algorithmic biases in the curation of content users consume. Moreover, as these platforms expand their reach, the ripple effects of exclusion can have serious consequences for people’s personal and professional lives, and users have no clear path to recourse. The platforms that host and inform our networked public sphere are unelected, unaccountable, and often impossible to audit or oversee.

In response, there is a growing movement among free speech advocates to create new technology to address these concerns. Early web pioneers like Brewster Kahle have called for ways we might “lock the web open” with code, enabling peer-to-peer interactions in place of mediated private platforms. The idea is to return to the good old days of the early '90’s web, when users published content directly in a user-friendly decentralized fashion, without the need for corporate intermediaries and their aspirational approach.

It’s an exciting idea. Instead of corporate-owned platforms, users could meet, flirt, argue, and share in user-run community forums. Many of these proposed platforms build on the concept of decentralization, which has grown increasingly popular with the rise of cryptocurrencies like bitcoin.

Similar to bitcoin, decentralized platforms have no single organization controlling the network. The decentralized web employs technology that eliminates such choke points in the technical infrastructure of the web. This has given rise to projects like Mastodon, a federated social media platform that resembles Twitter; Blockstack, a distributed system for online identity services; and Steemit, an online community using digital tokens to encourage people to contribute to a Reddit-like online community.

The three of us investigated several of these most promising efforts to “re-decentralize” the web, to better understand their potential to shake up the dominance of Facebook, Google, and Twitter. The projects we examined are pursuing deeply exciting new ideas. However, we doubt that decentralized systems alone will address the threats to free expression caused by today’s mega-platforms, for several key reasons.

First, these tools will face challenges acquiring users and gaining the attention of developers. Tools like Diaspora and FreedomBox encountered difficulties attracting a permanent user base, and it’s likely new platforms will, too. Social networks, in particular, are difficult to bootstrap due to network effects—we join them because our friends are there, not for ideological reasons like decentralization. And while existing social networks have perfected their interfaces based on feedback from millions of users, new social networks are often challenging for new users to navigate.

These platforms also pose new security threats. Decentralized networks generally allow anyone to join and don’t link accounts to real-world identities like phone numbers. These systems often use public key cryptography to ensure account security. But managing public keys is hard for most users, and building software that is both cryptographically secure and easy to use is difficult.

Social media platforms are curators, not just publishers. Platforms like Facebook control not only what is acceptable to publish, but what posts we see, bringing the most interesting posts to one’s attention. Platforms tend to optimize for advertising revenue, prioritizing attention-grabbing or feel-good content. Designing robust reward mechanisms to curate content that keeps people informed rather than entertained remains a problem. If distributed platforms could solve it, they could theoretically tackle media challenges like echo chambers and filter bubbles, but such dilemmas still present a serious challenge for new systems.