What ever happened to the increase in inventory slots

[Squintina]

It's related because the reason why we can get inventory increase is because "server stability" how does paying 5 dollars for an app magically buff servers to surpass or overcome this stability issue

I get all that but you are strawmaning.

You asked about the second inventory addition.
We got the second inventory addition.

Whether or not they wanted to give a different version of the addition, or whether they should provide a 3rd sub-included addition, but somehow aren't getting them because they're going to put that behind an app - while certainly an interesting subject - is not what you originally asked nor is it particularly relevant. It is tangentially relevant, not directly.

And while I don't like the app sub either, I can actually think of a reason why it would be possible to give more space via a paywall than via the included sub because I try to think about all sides and not just live in a bubble of negative melodrama.

And that simply the majority of players, which they can see on their stats, do not make use of extra retainers at all as it is. Thus the majority of players will not be using the extra 5$ sub for more saddlebag and the ability to purchase one more retainers. Thus they can plan for space that would only for X% of players based on statistical data. If they included it in the sub, that would need 100% player coverage (regardless of whether the user uses it or not, it would need to be allocated).

Would I prefer if they upgraded their system to cover the 100% playerbase for a 3rd expansion? ABSOLUTELY
Do I think any chocobo saddlebag expansion should be accessible to players even if extra retainers remained paid? OH HELL YES
Do I think the paid retainers were BS to begin with? YOU BETCHA

But is that relevant to the chocobo saddlebag being the answer to your original question? not one bit

You also make the error of assuming that all inventory would have equal effects to server stability.

Perhaps they did want to do 2 Player Inventory expansions, but technical issues (from their obviously atrocious spaghetti code) made it impossible to stabilize. The chocobo saddlebag, being separate and having different requirements is most likely using a different form of storage that has its own code that hopefully uses a better transfer netcode to stabilize and could have been the only way to provide the promised expansion without destroying server stability.

Likewise retainers, as they've stated or hinted in the past, are stored on their own servers and that is why they have to be summoned rather than accessed at any time. Once again pointing that this is different from player storage which has to be passed at all times. Thus the server communication impact of something like a retainer would be far less than that of expanding player inventory.

So you can't point at saddlebags and retainers as them lying about stability issues regarding the normal player inventory. They are separate systems, sent separately, with different requirements and restrictions.