None of these things actually do anything to inform WHY they are the way they are. The MA merit doesn't successfully express "You seek out tutors in the supernatural styles". You aren't engaged with the setting or the idea of your charcter learning martial arts- it's a non-choice. "I want MA, so I need this merit, because the game says so."
It's not a question of "Types of XP" it's a question of "Why are all of these different, if their differences aren't that meaningful?"
I'm not getting how they don't inform why they are the way they are, it feels like you're saying the mechanical reasons which actually do illustrate what's described in the fluff.
Like, going at it specifically:
3e MA is gated by a merit you spend XP on; it's taxed for some reason.
MA Charms aren't instinctual, they're techniques that are developed through rigorous practice. The merit seems to represent the foundational knowledge and practices required to prepare oneself to learn and successfully internalize MA charms, meaning that your regular Exalt, no matter how excellent he is, can't just walk in, have a past-life epiphany and quote Keanu Reeves. Doesn't that tell us why? They describe it in the merit.
Evocations are gated by "I have an Artifact in hand"
Evocation access seems to be gated by a few things, one of which being EXP.
Sometimes, instead of EXP, it's just attunement, so committing the motes so you can wield it automatically gives you some familiarity with the unique effects the weapon might have on your ability to fight.
Sometimes, it's free, but you gain the Evocation in a context specific scenario, so once you're near death, the armor saves you by activating the Evocation, and from then on, you know you can rely on it to provide that benefit when your enemy has you on the ropes.
All of this is tied to the weapon, because you're channeling your magical power whatever through its magical power whatever. You're fueling it, but the funky power in question comes from the Artifact combined with you, and the possibility that others might not be able to unlock the Evocations you did from the artifact suggest not only the artifact's unique story, but that unique story as it has to do with you, as one of its unique wielders.
All those things definitely seem to have answers for why they are the way they are, which are evident in the way they describe the relationship between Exalts and Evocations, and the variety of ways they can be mechanically unlocked.
Regular Charms are not gated at all- you buy them straight out
They explain at the start of 3e's Charm section that Solars can intuit these abilities and extra capabilities by tapping into the arete that their Solar Exaltation provides. It's the natural expression of their Solar ability Excellence, so the only thing that gates it is your skill in the Ability in question. If you cultivate the Ability, you can cultivate unique powers that augment or bud off from your excellence with that skill. That the possibility to do this thing is intrinsic to the Solar condition seems to be providing an answer for why it works the way it does at the start of the Charm section, and in how you buy them.
None of these things actually do anything to inform WHY they are the way they are. The MA merit doesn't successfully express "You seek out tutors in the supernatural styles". You aren't engaged with the setting or the idea of your charcter learning martial arts- it's a non-choice. "I want MA, so I need this merit, because the game says so."
What is the metric for successfully expressing the idea? I mean, it literally says that you've undergone systemic formal training, and even provides the example of how a character might have been raised as an Immaculate Monk, or studied in a dojo over the course of their adventures.
Like, I can't follow how that isn't telling you why it is the way it is. Martial Arts require a foundation of systemic formal training to learn how to use them, and that systemic formal training that underlies martial arts is represented in the Merit. I get being annoyed by the merit, but it doesn't seem like it fails to explain itself.
It's not a question of "Types of XP" it's a question of "Why are all of these different, if their differences aren't that meaningful?"
So is the complaint that Martial Arts, Solar Charms and Evocations aren't different enough from each other? They seem to come from three different sources that work differently, so in terms of narrative they do seem to explain why these things are different in lore.
Mechanically, they all seem to use the same written format to communicate the different powers they have. I guess that's pretty similar. Is it an issue of formatting for you? Because Sorcery is differently formatted from MA Charms, Solar Charms and Evocations, do you think that it doesn't fall into the same issue that these other things seem to?
Again, this sounds like it might be an Exalted issue rather than a 3e issue if I'm parsing what's being said correctly.