Those are fair points. Let me answer them.
The problem with always adding qualifiers (e.g. "in general," "in many cases," "broadly speaking") isn't that it takes to much time to write, but that it makes prose clunky and tedious. Littering your writing with endless qualifying phrases makes it annoying as hell to read.
As far as the example, I think it is case of apples and oranges. We don't need to speculate about whether uppercuts and right crosses are effective--we KNOW they are. The reason we know is because they are constantly tested under realistic conditions. This is not the case with many (NOT ALL!!!!) TMA techniques because, generally speaking (THERE ARE EXCEPTIONS!!!) they are not testing under anything even vaguely approaching realistic conditions.