The problem with FF version of level scaling is that it makes content worse over time. In ARR 2.0 the level 50 content let you use the full extend of your class' skillset. And while that skillset had very different abilities than a level 90 skillset nowadays, it still felt like playing a fully developed class. But now classes have so few abilities at level 50, it feels a bit like a level 1 class doing starter quest for hunting boars. And if FF continues to progress like in the past, that will get worse up the level stack more and more.

The arguments about level 50 content that isn't designed for level 90 abilities is not valid afaik. That level 50 content was originally designed for very different classes anyway. And those higher level abilities do not sufficiently create new gameplay mechanics that trivialize content. It's more about balancing damage/healing/mitigation, and that is actually easier at level 90 than with existing level scaling. At level 50 class balance is completely out of the window. It would be much preferable to take the far better balanced level 90 classes, and only give them potency/mitigation nerfs when level scaling to bring them in line with lower level content.

So I fully agree level scaling should be changed, both for balance and for fun.