I agree - but if one person can look at it and see "mythic", and another look at it and see "mundane + satisfactory explanation for mythic capabilities", that's probably a good thing.
Yes. I'm riffing off your response rather than responding to anything in particular.
The explanation is most definitely a good things in many contexts, especially when you are actually playing the game (with possible exception here for certain DM tasks). It's more ambiguous during development and presentation of the game, and often bad during design (though somewhat necessary even there). In the analysis that precedes design, the illusion that it is anything but mythic is almost universally bad.
I don't think anyone comes down harder on "illusionism" than I do, but despite my extreme dislike of "illusionism" I see a very valid, positive role for illusion itself. It's the almost fetish-like cult that grows around illusion that I think of as "illusionism"--and mostly negative.
So the illusion that a mundane character has a satisfactory explanation for mythic capabilities--during play--is highly useful and necessary. We can see it most clearly with an absurb example. Let's give the fighter the ability to teleport freely, anytime, anywhere, at-will, with no explanation whatsoever? No one
is buying that. And even if you tone it down so that it isn't overpowered, still no one is buying that. Take that toned down power and give it a rationalization--magic item, fey blood, some kind of fighter/mage backing, etc., suddenly it's fine for some people. Come up with enough options, practically no one will object, and most of the objections will be mild and/or purely based upon taste--"Well, I still don't like it for flavor, but I don't see any real problem with it for those that like it." Some people have that reaction to magic missile
, after all.
In contrast, what grows out of illusionism is somehow that the rationalization itself is self-justifying. For example, this guy has fey blood. The fey teleport. Ergo, this guy teleports. That's even fine as a starting place. But then it turns out that when some say, "The fey teleport," what they mean is that, "The fey teleport in particular ways, and with particular power," because that's the way it's always been, because of particular literary preferences, or other such. And then it turns out that when you go to put limits on the power, you can't put simple ones, because you are working around the rationalization.
At that point, the illusion is driving the mechanics, instead of being something that, we hope, is expressed by the mechanics. The designers have bought into their own illusion instead of crafting the illusion. You can't be a great magician and at the same time be fooled by your own tricks.
I think it is Dausuul who is fond of saying that flavor and crunch are useless concepts, that the two are inseparable and thus attempts to separate them do damage to the game elements. If I understand the idea correctly, then I disagree. However, the illusion and mechanics do need to be considered from the very beginning of development. So if that is what Dausuul means, I'm buying his newsletter. I merely think that keeping them both conceptually separate in the head of the author, but practically merged in the presentation, is the best way for the end user to experience them as satisfactorily whole in the end.
Ideally, then, you'd have design notes elsewhere to help the DM, because when the DM starts changing things around, he has become a bit of an analyst/designer, and thus it becomes useful for him to see the separate concepts.