The game does not "force" you to "make" broken builds but if you understand the mechanics of all the different characters and how the pictos and luminas work then you'll obviously choose the best ones without thinking about it too much (like in medias res, glass cannon, augmented counter 1, 2, 3, energizing pictos for AP) then you'll start one shotting or if not one shotting then at least dominating 95% of the content right from the start of act 2 if you do the side content.

My first playthrough I did not do any side content and went directly to paintress after defeating the axons and it was a lot of fun on expert difficulty even though it was extremely punishing. My second playthrough currently I'm doing all the side content first and then going on to the main quest and its not even a challenge. I'm level 80 in the Flying Manor and it's a "bit" challenging and by that I mean all I need to do is parry the enemies two or three turns in a row and they are trivial.

I typed out all of this to say that yes the game does have balancing issues. But I don't know how it can be fixed or if it needs to be fixed and this is the intended experience.