While there are obvious flaws with the analogy (like any analogy), I think the comparison with eyesight (or touch, etc.) is about making people think of the mind as more of a sensory organ. One that gives you input that may or may not be useful to you, rather than as something that defines you.
I don't really see that as a dissociative practice, but more as the prerequisite for being able to start on the long term journey of challenging and changing your thought patterns.
From my perspective, thoughts are the sensory experience of 'my mind moving'. Similar to arm movements - when you move your arm, where does the motion come from?
I'm reminded of a time in my childhood when I realized that I could consciously direct my eyes without turning my head. I was struck with wonder at the time, having not known such a thing was possible, because nobody told me. I still remember it vividly by the impact it had on me. The more I converse on this topic, the more I see people considering the mind as I had considered my eyes prior to my childhood realization.
The point I'm trying to get to is that I believe the dichotomy of mind and the body is a false one. I think the abstraction level of 'mind' is different from the level of 'body'. It should rather be 'mind' and 'arm' and 'eye' (and etc.).
The command of these in concert is somewhere outside of my perception, or so deep inside of it that I am blinded by its normality. Calling something we can't perceive by the name of something we can, I think, is magical thinking and folly. Why are my thoughts this way? Because my Mind. Why do planets orbit stars? Because Science. Why are we alive? Because we have élan vital.
Looking at it this way, the impossibility of controlling thoughts is lifted. When thoughts are solely something that happen to you, the very notion of controlling them except indirectly is incoherent. But re-framed, I can train my mind as I would train skill or form in body.
I know that I can't play the cello with any skill, as I am now. If I try, it will grate on the listener and cause more displeasure than pleasure. It's not an inherent failing of mine, simply that I haven't devoted the requisite time and energy to train myself in it. But it does define me, at least in part.
Would that skillful thinking was perceived the same as skillful cello playing. Instead, educational institutions must suffice to verify that you have the tools (in the form of knowledge, or acquired frameworks), but say little of skill achieved. Imagine a 4 year cello playing course in which a passing grade is earned if you but present a cello at the end.
I think that if this concept is fully integrated, outcomes would be better. If the mind is viewed as an intangible thing that blasts thoughts in your general direction, from where can it be improved? I know my body can be improved, by strenuous exercise. I know my skill at cello can be improved, if I simply practice. But my mind? If I'm hamstrung by its conception as a pure source, I'll forever stay at whatever minimal level is required to survive. And that's a tragedy.
This went a little off into conjecture-land, but I think I'll leave it for the time being.
You describe thoughts as if you are in receivership of them, like a mom receiving a work of art from her child.
I can direct and focus my thoughts beyond their capacity to perceive the world, like channeling attention and sculpting potential words when I am typing out this comment. I can direct myself to imagine worlds that never existed and solve problems in the future, which requires directed thought.
Your mind is trivially easy to improve, conceptually. Focused improvement on a hard skill will drag your mind along. Deciding to get better at cello will require you to learn higher concepts of music reading, fine motor skills and playing in a band that will form a structure in your mind. That will make thinking and directing thoughts in new directions much easier. It's much easier to ask someone to imagine what it's like working in a construction team building a shopping mall when they know how people work together in a band, compared to a blank slate that knows nothing. That imagination can be used to prune off bad ideas and thoughts that go nowhere.
The educational institution that is supposed to be good at this is the humanities. Philosophy will train you to express your mind through language at such an articulated level that you will know yourself better and be able to navigate a very wide array of arguments with precision. Thus giving you a much better source of material for your mind to sculpt it's thoughts with.
The mind simply has to be pure to sort signal from noise, that's a fundamental part of what it does. The mind is also incorporeal, it has the least matter. The higher you think, the less quantities of properties and details you can focus on. Their totality is summed up as categories that start doing all that heavy lifting for you in implied abstractions. Keeping track of hundreds of different sized numbers and the properties of each item you are counting in one holistic picture is difficult. Purifying that into abstractions and relations between them is incredibly powerful.
Do you centre your being on the spine, rather than the mind? Framing and receiving the output of the mind is what a lot of people do and I hazard a guess the ability to balance the difference between quantities and directions is a lot easier when you hang that task on the spine, with limbs that protrude out from it.
I don't really see that as a dissociative practice, but more as the prerequisite for being able to start on the long term journey of challenging and changing your thought patterns.