The point is that having the missed tactics pointed out to you by the computer doesn't do much to improve your chess. It won't help you find a tactic the next time an opportunity comes up. Whereas analyzing seriously and finding tactics yourself (albeit fewer than the computer will point out), _will_ improve your ability to find them over the board.
I differ from you in that regard. I learn tactics by seeing them played out. Once I see the pattern, it gets burned into my memory a bit, especially if I missed a tactic that led to my defeat.
