If you are saying that the PC is a wizard, but for some reason can't do what every other apprentice wizard can do, then the problem seems to me to be not one of dissociation, but a more basic one of coherence, or at least of verisimilitude.
I said it was undefined. Then I went on to qualify that contention by noting page 42 and the general advice provided about how to handle such situations. "Undefined" here was called out as meaning, strictly undefined by RAW--and implies a very literal reading of the RAW. Once once has absorbed the import of the provided advice, then I agree with you. No doubt, playing other games with similar sensibilities made this more apparent at the launch of 4E, whereas some of the advice didn't arrive until DMG 2, and some still hasn't made it.
All of the below is IMO, YMMV.
Any fantasy/sci-fi medium has the problem of incorporating new technologies or magical elements into their worldbuilding:
I'm sure that screenwriters struggled with the adoption of the cell phone in real-life. Many movie plot devices were all based on the landline phone. Now you deal with it by either a) setting the movie in the 80s or earlier, or b) make up an excuse for why your cell phone isn't working, or c) adapting the plot to cell phones for a different story. All 3 approaches are legitimate, although (b) only works for any one scenario in one movie, and only (c) really rolls with that reality.
There is option (d) -- a movie set in 2011 where no character uses a cell phone even if they could and didn't have an excuse not to. That's disassociated to me...
D&D could have been completely surreal, but it isn't. There's something to be said for familiarity. D&D draws upon familiar elements in literature and movies and mythology, like dragons, Medusa's gaze, princes transformed to frogs, magic flying carpets, truth serums, Jedi mind trick, and so forth.
Earlier editions of D&D attempted to import these familiar fictional constructs, resulting in a) more fantasy and wonder, but having to account for b) game balance and worldbuilding. I think when it came to balancing (a) vs (b), the designers leaned towards (a) more fantasy and wonder.
Yes, that could result in problems, but..
with zones of truth, you can a) not even notice the implications -- true in my experience, b) notice it but purposefully gloss over it, c) houserule it out of existence, d) introduce in-game reasons to restrict its use by NPCs, e) just roll with it and work the stories around it.
I think the designers knew that there was a social contract in place and houserulings to buffer against potential problems, and gosh darn it, it was worth it to have more fantasy and wonder in the game! IMO I would have pushed slightly more towards (b) but still with an eye on (a).
4E plays it safest due to its focus on combat-informed tactics and game balance. So Medusa's instant-flesh-to-stone gaze becomes a more gradual thing. Permanent polymorph until dispelled becomes a 6 second duration. Magic carpets are prohibitively expensive. Hypnotism begins as a binary effect. IMO I acknowledge the underlying goals but I think it went too far.
Personally, I think, IMO, YMMV, and accepting no responsibility for substantiating the factuality of my opinion, I think it's like D&D was a toy box full of all sorts of wonderful and colorful toys, some of which could be slightly dangerous and caused some babies to cry but were otherwise amazing toys to play with if you were emotionally mature with sharing toys, and then 4E came and took away all the sharp-edged colorful toys and left you with soft rounded toys in a padded room for your own protection -- and if you decide to stray out of the play area (through a somewhat hidden door marked 'Page 42') and create your own new toys, you do so at YOUR OWN RISK. Otherwise, you can peer through the windows of your play area and watch other kids playing with slightly dangerous but very fun colorful wonderous toys that you cannot have (this is where one type of "disassociation" comes in for me, the disconnect between your play area vs the outside world). It seems that the designers don't trust you to behave, or they just haven't figured out what to do with the fun but slightly dangerous toys so they discontinue them until they find a way to literally nerf them for your protection.
And yes, that was always happening to some extent in D&D, except that to avoid disassociation, I think most toys were designed to work more or less the same in the play area and the outside world. and if the toy worked differently in the play area vs the outside world, there was a fictional reason for it. If the toy was too dangerous, like a nuclear bomb, it would not be included at all, but you wouldn't have a half-assed half-nuclear bomb as a sort of poor man's compromise between nuclear bomb or no nuclear bomb. I think it's better to have no item at all than an item so nerfed it no longer resembles the fiction you're familiar with (Crazy Jerome, is that anything like your "fairy tale logic" that a non-greedy dragon isn't a dragon?).
I think it's interesting to note that dragons and all sorts of horrible monsters exist in the game alongside small villages to large cities. If this fiction was attacked aggressively with the same hardnosed approach to Zones of Truth and Walls of Iron, I think it could be asked why isn't the world completely overrun with monsters while the weaker races hide in holes and grub in the dirt, like the early mammals did during the reign of the dinosaurs? There's also a broken economy and so forth. Clearly, there are some unrealized worldbuilding issues in any D&D setting, but this doesn't seem to be a significant problem. The designers can be trusted to introduce dragons and so forth that integrate with the world, and the players can be trusted to use any narrative they want to fluff the mechanics that they're allowed to use, and they can even be trusted to use any narrative to justify oddball cases like marking an ooze or tripping a snake, but the PCs cannot be trusted (by default anyway) to interact with or use tools that might alter the game world in unexpected ways. As you drill down to all the mechanics behind this paradigm, it seems to me that this paradigm may partially inform some of the "disassociated mechanics" that can exist when you think your PC *could* do something but seemingly arbitrarily cannot or when a player does something mechanically that you cannot quite explain why/how the PC is doing so within the context of the game world.
So if you play strictly by the rules, there's a certain spectrum of fantasy roleplaying you'll ever get. If this bothers you, and if you're still playing 4E, and if you allow for more use of Page 42, and if you're not afraid of upsetting game balance and worldbuilding, and if you have a solid social contract between the DMs and players, (and by this point, a large fraction of gaming groups are eliminated), then you can expand the worldbuilding to include more advanced/swingy fantasy elements. Since you're going at it solo, with no guidelines, like a pioneer, it's a very different experience, like writing your own mini-RPG system. You might end up like Lost or Battlestar Galactica, starting off strong and then meandering and diverging and retconning and leaving behind plotholes and lost threads as your write every season on the fly without a long term vision for how all the new elements integrate into your gameworld. Some people enjoy equally every episode of Lost and BSG, but others wished that the screenwriters had a more coherent vision from the get-go.
So yes, the mechanics are excellent for their design intent. Yet going back to the 1st post of page 50 of this thread, I think one can have "disassociation" when one defines the Rule as Page 42 and defines the Fiction as the story of the PCs and their relationship to a game world that is potentially dynamic and variable in the hands of any one gaming group. I don't know that Page 42 on its own is robust enough in the hands of any one DM to tell the stories that will prevent "disassociation" for the scope of an evolved post-4e campaign or game world. And if one gives up and does away with all that, then one circles back to the top of this post...
And I don't know that fingers recently pointed at 3E, no matter how justified, prove that 3E is more "disassociated" than 4E, assuming that's an interesting discussion to have. IMO I'm waiting for Mearls' hints at 5E and layers that might bridge the divide.
DISCLAIMER: All of the above is IMO, YMMV. I'm not purposefully attempting to disprove anyone's opinions, and I'm willing to agree to disagree. Please accept my apologies in advance for any semantic errors or opinions that conflict with yours.