One of the big differences between me, somebody who can actually relate to that feeling of being pianistically underdeveloped, and other posters who merely claim to understand the psychology and what it's like to teach adults in this situation (but don't have any idea about what it's actually like), is that I don't find anything within it that is something to joke about, treat as insignificant in any way, shape or form, nor make light of in any way - especially not in a thread that is presumably sincere.
I understand that there may be something different about my personal experience growing up without formal lessons and training, vs. many other adults who start learning as an adult. I could simply comprehend what I felt the OP was trying to say regarding feeling like his musical development was only developed so far. My point was always that it is one thing to relate to life and even to music as an adult, it is another to be capable of expressing that relationship through one's playing, and I think that is important for a teacher to understand since that gap can create its own problem. I don't think it's psychologically helpful to simply state to them they are an adult and that they therefore do and should relate to music as an adult vs. a teenager.
Personally, I have needed teachers to understand this about me on some level, even if they can't fundamentally or personally relate. And there are things about it, at least in my own case, that feel inexplicably terrible and which, as I have stated before on this forum, have created for me quite large and pronounced problems (which I see now could have been avoided), beyond me feeling shy about playing or pounding my fists on the piano in front of teachers I deeply admire. In my case, I can feel myself actually developing as a person as I develop as a pianist, as a singer, and as a musician (but especially as a pianist). There is nobody who can change that fact, it's simply part of who I am.
I certainly don't expect it to hold me back forever, I am certainly extremely grateful for my very amazing teachers (and admittedly for this forum), but there is no way I could skip any steps and expect to get the same result as somebody who did not skip steps. And that's the real point. Personally I wouldn't want to be treated as though I could skip steps which in doing so creates or nurtures gaps, simply because I'm an adult and have developed in certain areas. There is no question I have a lot more developing to do as a musician/pianist, and I don't want to be robbed of that because somebody is deceived by my adultyness. I assume other adults who might be passionate about their musical endeavors might feel similarly ... but I recognize I am probably even some steps beyond being merely passionate about it.
If that is helpful for somebody, I am truly happy. If it is not then it's not. All the same, I've got steps to take and I seek ways to take them.