Why are applications the current "size"?

That is, what determines whether we have lots of little, specific apps or a small number of large, general purpose ones?

Probably a lot of factors, but one that I think is important is what I'd call the Coasian theory of the app.

That is, the app size is determined partially by the coordination cost of integrating your app with another party's system.

Code is unforgiving; when two systems need to interact it's like finely machined gears that have to mesh perfectly with the gears around them.

If you made both of the gears, it's easy to make sure they enmesh, and also easier to modify both at the same time.

But if your gear has to enmesh with someone else's gear (or maybe a lot of different someone's) then it's more of a pain and you might decide to bring the other side in house too.

Part of this cost is "how expensive is it to write code to enmesh well with the APIs of external systems."

But now we can compile english to code.

So in a post-app world that is LLM-native, you might expect to see a larger number of smaller apps.