content: Mastodon itself is an implementation of what is called the ActivityPub protocol. It is a twitter like UI. So your question is probably related to ActivityPub, not mastodon. ActivityPub is a spec that anyone can implement to create a social network of some sort. It allows any server running a social network to communicate with any other server running the same network and in most cases, any other network that uses ActivityPub. So theoretically you could subscribe to a user profile on a Facebook like network from your twitter like network (Mastodon) account. Yes, it can be used and is being used to change the way social networks work. It is changing them from social "platforms" to actual networks.