More Horizontal Progression please

[Ibi]

That isn't Horizontal Progression. That is forced Vertical Progression. There is no other choice if one choice is 100% better.

Vertical progression is when you can replace one item with another, in all situations. Horizontal progression is when an item can replace your existing item in some cases, but not other cases (like LineageRazor described).

Even in horizontal progression, there's still going to be a superior option in any given situation, unless the trade off is something like survivability vs. throughput (which is one of the very few choices that actually does already exist in FFXIV).

Unless you have some other definition of horizontal progression.