Why does Pathfinder inherit well-known 3.5e imbalances?

In terms of class, it is well known that the 3.5th PHB is not well balanced (for example, it has classes going from level 1 to level 5) outside perhaps very early levels, while subsequent Battle Tome and the Extended Psionics Manual are not only much better balanced, but probably much better written (see the links, I am referring to the range of class levels they contain and the frequency of revolutionary exploits or the choice of traps for the characters). Indeed, although I find it difficult to find sources, I am aware of the fact that many groups completely forbid PHB classes (that is, "forbid Core") for the reasons that I have. I listed. Naturally, it is difficult to introduce new players into these groups *, but even relying on the recommendations of the tiered system, this seems like an almost inevitable choice.

That brings me to my question. I have little doubt that the developers of Scout were aware of the problems I've listed and the common tactics used by 3.5e players to solve them. So, in the event that the developers wanted to create a more balanced game than 3.5e, why did they choose to follow the very defective 3.5th PHB so closely? I am aware that they have made changes to the main classes, but I am also aware that their changes have had very little effect and have probably worsened the situation. Is it really just the case that they completely deny that the problem exists?

* You can easily imagine the scene "read this book to know the rules, but ignore half and read it rather, I promise you that this game is good …"