But, hang on, if psionics is drawn from the Far Realms, then is specifically
isn't just another kind of magic. Magic in D&D does not draw on any planes at all. Magic in core D&D draws on the Weave. Or it's granted by gods, using the weave. If we ignore 5e lore, where does arcane magic come from? Has any edition of D&D actually spelled it out (sorry about the pun)? Previous editions had gods granting divine magic, except when they didn't, because in 1e (and 2e?) 1st and 2nd level cleric spells didn't come from any gods, they just came from the devotion of the cleric.
But, supernatural power from the unknowable beyond has never been applied to any system of magic in D&D has it? As far as a "source" for psionics, the books have been mostly silent. There is very little lore to base anything on. If psionics is inherent, then do we need to start having systems for deciding if every single Monster Manual creature has psionics at any given time? If humans and dwarves and halflings can be psionic, why can't orcs and goblins and kobolds?
And, if it's an inherent trait, how do we jive this with mind flayers and aboleth? Why are they psionic? The species just has a natural affinity? But, how does that explain Demons and Devils being psionic? They aren't a species at all. They don't have inherent traits. They don't have a biology to speak of. Can undead be psionic? How does that work when a spirit doesn't actually have a physical brain? What inherent traits are being utilised here? On and on and on.
But, if psionics is something that you access, either through natural talent or training, suddenly all those issues go away. Some creatures are naturally psionic, and considering it's all the weird stuff that's already tied to the Far Realms, it does tie the lore of the game together nicely. Aboleth and Mind Flayers are the way they are because of Far Realms ties. Makes sense.
It's not like WOTC is creating this stuff whole cloth here. It's been in the game for a while in various forms. They're just cleaning things up.
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On a side note, it's really ironic. I argues vehemently against including lore in the 5e Monster Manual. I hate it. I really do. I think the 5e Monster Manual is a waste of space. But, everyone told me I was 100% wrong and that the game needs lore and that lore is important. Well, you got what you wished for. You want a game that's tied together with lore, well, here it is in spades. Funny how when it suddenly applies to people's favourite pet part of the game, it's a bad thing.
Careful what you wish for.