We all know LI is overpowered but if people trained more players for different tactics, rather than just LI players, it would make other tactics more powerful because, as you say, teams could buy players more suited to motion, princeton etc.. Marin has said something along those kind of lines too.
You make some valid points but a lot of say what you say is bordering on Trainerman territory (sorry Trainerman) and its difficult to have a discussion with somebody who is just posting lengthy polemics.