I'm writing a fantasy story that I hope to make more relatable to the modern day by the inclusion of a psychic "internet." At some point in the last two or three centuries this world discovered the means by which to tap into the web of psychic threads connecting all living things, and quickly developed the means by which to share information across vast distances instantaneously. Governments quickly developed new forms of psychic communication and espionage, and even the poorest peasant can manage a connection to the public channels of psychic discourse. Otherwise, however, technology is much the same as it was, lacking printing presses, steam engines, and the like.
What are some of the biggest departures this world might make from our own following this development? Thanks.
EDIT: some notes on the mechanics of this "internet"
It's still up for reimagining, but at the moment this web is a series of psychic "spaces" not unlike a "method of loci" / mind palace, although someone accessing such a space need not picture it continuously in perfect detail to be present within it. Conjuring up such a space (a small one, at least) is trivial, as is finding a space that the original conjurer has deemed open to visitation. You can also open up a space for a particular person or kind of person.
To share something with another, one simply imagines it into being within the "space," conjuring a replica with a level of verisimilitude that varies depending on one's knowledge of the subject and imaginative ability. Speaking or conjuring a written message in such a space is trivial.
Larger spaces — the forums, town facebook walls, and social media equivalents of this world usually require the talents of one or more trained "servers," those who have cultivated their imaginative capacity enough to maintain an elaborate locus for an extended period of time.
The information comprising one of these psychic spaces is stored within the physical mind of its conjurer - accessing one without its creator's permission is either a matter of avoiding their detection or making physical contact with them in the material world.
Servers can act as an effective store of their own and others' knowledge, and can access the contents of their own locus at any time whether they're "online" or not. Entire libraries might be contained within the brain of a single man, although such a server wouldn't possess that knowledge in the same way as a trained expert. If such an expert were to collect their years of knowledge into a psychic "book," they could easily deposit it into the mind of a server. That server would then be able to "read" that book whenever they wished, which would take about as long as reading it physically. The advantage here isn't as much matrix-style "download kung-fu skills" as it is "I have an entire invisible library inside my head that I can invisibly reference at any time."
Regarding storage and degradation of servers' information — as servers don't "own" their psychic memories in the same way we do, I don't think they can "forget" them in the same way either. A stored symbol will remain as it is in perpetuity, assuming no damage to the physical storage medium. Dementia, head trauma, or any kind of degenerative brain disease might warp or destroy stored symbols.
Within such a space a person appears as they imagine themselves, unless they or another within the space makes a conscious effort to conceal one or more participants' identities. Imagining a false or artificial psychic avatar is also possible, but a savvy psychic can spot someone assuming a false identity. Although in such a situation it may be possible to uncover the suspect's real identity, the arms race to develop new psychic technologies is without end.
Regarding attacks made over this psychic network — it is possible to knock a server unconscious or perhaps even drive them insane if they are caught unawares by an onslaught of demands, but air-gapping is a simple matter of making a split-second decision to disconnect oneself from the network.
Regarding the speed of communication — accessing a locus/site/space is instantaneous, however conjuring a readable record within that space proceeds at the speed of thought / a speed roughly equal to that of typing. A user needs to put their ideas into words, images, or some other form of symbol to be understood. Just like in our world, speech and conjured text can only be understood if all parties to a conversation share a language, although some concepts like images or 3d objects can be understood by all, encouraging separate psychic spheres for separate nations or languages. (Just like how in our world, most users on the english-speaking internet have little knowledge of the goings-on on Weibo)
Memes and "Cyber" warfare
What's an internet without memes, grifters, and influencers? Regarding memes — Earworms and other self-propagating symbols are ever-present facets of the psychic world, reinscribed into being by humans both consciously and subconsciously. These objects can be harmless, or more sinister: memetic objects might be difficult to destroy, might be dangerously seductive and addictive, might whisper provocative lies, or might even pose a violent threat to servers and other visitors to a site. (@jdunlop has also provided some very cool ideas for psychic memes in chat, but I'm not sure if it's proper StackExchange etiquette to include those in this document. Go check them out!)
Regarding religion and stochastic terrorism — @MJ713 made some very good points about religion that I would definitely like to address. First of all, established religion: dogma surrounding the origin and function of the psychic world is a staple of large state-supported religions, and I imagine convincing your populous that the psychic world in some way supersedes the physical is an effective way of keeping them docile and subservient to authority. Another point MJ made was that of false gods or other psychic demagogues, those who can convince the average person of their divinity by virtue of their arguments, claims, or imaginative talents. Such figures might be content with the fawning praise and attention of their followers, but many would take the opportunity to encourage action in the material world, safe in the assumption that any consequences likely won't apply to them.