The role of tactics

J'adoube is hammering on the fact that tactics flow naturally from a good position. Well, that's true without a doubt. But it isn't the only role of tactics. Maybe it isn't even the most important role.

PCT learns me to play healthy moves.
Given the fact that I score about 50% with new problems, I already know how to play unhealthy moves.
That has a lot to do with the evaluation of the position. What do I assess as the most important fact in the position? Since I always go for the king, this influences my assessment. I always want to keep a piece on the board, because without pieces I can't attack.
And that is a critical component in the assessment. The GM that assessed the problems of PCT, based that assessment on his own skills. If I assess the same position different, it is because I don't have the same skills. I you screw up any endgame, there's no need to be bothered by your pawn structure too much.
So basically PCT tells you which skills you are missing, compared with a grandmaster.

Once you have your positional assessment developed, tactics get another role. Tactics become the MEANS by which you realize your formulated goals. Once you assessed that you should trade your bad bishop against a good one, you have to find the means to do so. That's where tactics come into play.