T&E is the universal tool for any logic. For example, if a row is filled with 12345678_, what is the missing digit? 9. Is it a logic or T&E move? It looks logic to many; but from the view of T&E, it is still a T&E, because "if 1 is there (a trial), there is a duplicate (an error)" and so on.
However, people still tend to treat this move as a logic one, because there is a pattern there and you do not have to use frank T&E. The pattern is "9 is missing and there is only position left", so that you save frank tirals of 1, 2, 3, ...
Another thing: logic pattern, when explained, can only be presented in the form of T&E. E.g., simple x-wing. When an X-wing of digit d is identified, digit d in other rows on the same columns must be removed. If you are asked "why?", you probably will answer in this way: "this is because the x-wing disallows it to be there.", "but why is that?", the you have to answer: "this is because if d is there (a trial), there will be duplicate of d in these columns (an error)". So my point is, the explanation may sound like T&E, but the logic may still be valid.
But I will agree with you and Jinjing that some advanced logic strategies have controvensial T&E quality.
