> It's impossible to have a 1:1 teacher to student ratio in common education.

Well, this assertion of impossibility is demonstrably and historically false, because since the times of Ancient Greece, that is how precisely how many people in the upper classes and great thinkers received their education.

It's also within the realm of economic possibility to have a 1:1 teacher to student ratio today for most disciplines while simultaneously expanding education access.

You do it by only supplying lectures in the form of video recordings by the single foremost expert lecturer on that topic, drastically reducing non-tutoring related administrative expenditures and overheads, crowd-sourcing free tutors from all age groups and professional backgrounds including non-academics, and gradually replacing public education funding with a voucher system for parents to go out, find, and pay for the best and most academically qualified tutors and mentors for their children in a competitive education market.

A lecture which proceeds at a pacing not controlled by the individual, in which the learner cannot interrogate each and every claim and proposition at their own pace in the order it is presented, is largely a dramatic performance. It's little more than a motivational speech for them go out and acquire the knowledge on their own time, outside of lecture, at a future date.

Instead of having thousands of teachers perform daily motivational speeches on the same topic nationwide, you can just have the single best speaker on the topic make a single recording once every few years using modern technology, and pay all of those workers to expend their labor on performing 1:1 interaction to accelerate the rate of learning.

> You can judge that by just looking at the plethora of experts graduating every year from numerous professions.

You cannot rationally judge the efficiency of an existing process in comparison to a proposed alternative by only observing the output of the existing one.

> The dialogue is a method and is used in class rooms and lectures when the students ask the teacher questions.

In a generalized form, dialogue is also conducted by learners internally through self questioning, and when engaging with an external medium which provides feedback (experimentation). It is a necessary experience for any learner to accept a new proposition as true, and something which one-to-many synchronous lectures are never directly capable of providing.

> earned in much shorter time span and to circumvent the limitations in teachers' capabilities and knowledge. Same for videos, internet, and so on.

Textbooks provide an essential aide for students engaged in self questioning to verify their answers, but as a static medium, they lack the ability to make predictions about what each learner is thinking based on observed behavioral cues like a tutor or peer can. Since static media cannot make efficient inferences about the individual based on reactive observation, it cannot tell each learner what they don't know they don't know.

Learning what you don't know you don't know is something which currently can only be efficiently achieved through conversation, and greatly accelerates the learning process.

> As for pathological behavior disorders, they are very real and vary in degree.

I would not argue that the phenomena which pathologies describe does not objectively exist, only that the principle which distinguishes atypical behavior from pathological behavior is a normative distinction containing embedded social-political beliefs rather than a purely descriptive one. It's an optional distinction to make, based on whether it provides us any utility any achieving our goals.

>It may be that you don't have first hand experience on how difficult those can be

I have met children with severe learning disabilities and it is widely accepted among teachers and parents that they are benefitted by more 1:1 interaction and shouldn't be stuck in large classrooms. My point is simply that everybody learns faster with 1:1 interaction and learns slower in large classrooms.