When "social media" meant "blogs," there were many tools, services and protocols that comprised an infrastructure for federated, open, loosely joined interaction: the rise of the social giants has killed off much of this infrastructure, all but erasing it from our memories.
Anil Dash compares the services and tools available in the new centralized web, and the new advantages of centralization, and also the lost functionality that disappeared with independent blogging. It must be said that some of these tools were already in critical condition as centralization took off, killed by the spam and other parasitic infestations that are endemic to complex, open ecosystems.
At the same time as early social tools were developing the ability for humans to follow other humans, users were recognizing that they wanted their software and tools to be able to subscribe to updates from their favorite sites. This could be for the purposes of reading sites more easily (see Aggregation and Time Shifting & Reading, below), or for use in automation or analysis tools. Though there were various attempts at syndication formats in the early days of the web, RSS took off as the signature format for blogging, and a protracted standards battle (akin to AMP vs. Instant Articles today, but with a lot more vitriol) produced the Atom format, which basically did the same thing. Syndication formats were useful not just for being machine-readable but because producing content in these formats implied a certain set of reuse and transformation permissions that was useful for software creators. Today, Google (along with Twitter and other partners) is pushing AMP, Facebook is pushing Instant Articles, and Apple is advocating its Apple News format (which is based on RSS). Though these formats are being motivated by a desire to improve the mobile reading experience, their goal of strict machine readability and their suitability to the tasks of aggregation, time shifting and easy reading make them a direct analog to RSS and other formats that came before.
The lost infrastructure of social media.