[horsawlarway]

So I do primarily App/Extension development, and I've been doing it for about 15 years now.

The short answer: You must have an interface you control, because app store review times mean there is no "hot fix".

When something upstream of the client breaks - you are DAYS (assume 24 to 48 hours for review, after you fix the bug) from being able to get a new client in front of users, and several weeks out from having all of your users (all being some accepted percentage - I use ~95% for my releases) actually update to the latest version.

If that "something upstream" is you - you can usually plan for it, release the updated client ahead of time, get it rolled out, then pull support for the old feature.

If that "something upstream" is reddit... They break things, and they might (but probably won't) inform you ahead of time. You will have many, many more outages.

[blint_carton]

Saved many long outages by being able to push quick dirty fixes to upstream APIs from our middle/server layer that depended on 3rd party APIs.

Also a place to pull in any access keys needed for other services if they connect to so it doesn't sit in the client code.