ProseMirror

ProseMirror is an open-source toolkit designed for building custom rich-text editors on the web. It provides a modular and extensible framework with features like collaborative editing, custom document schemas, and a plugin system. It serves as a foundational library for developers to create their own sophisticated editing interfaces.

ProseMirror is a toolkit for building rich-text editors, which directly aligns with the 'rich-text-editor' must-have feature. While it provides the foundational components for such an editor, it does not offer a complete publishing platform with built-in distribution, monetization, or comprehensive analytics as described in the concept. It focuses on the editor itself, with features like collaborative editing and extensible schemas, which are building blocks for a platform like Medium but not the full solution. The 'community-feedback-tools' is inferred from the collaborative editing feature, and 'user-profiles-and-following' and 'social-sharing-and-embedding' are common functionalities that can be built on top of ProseMirror, but not explicitly offered as part of its core toolkit.