But it's not necessarily because they use the old SDK that they are broken. And there have been betas available for some time

There are changes between each beta. There are also changes between the beta and GM.

Sure, but do those changes actually cause any apps compiled with the iOS 13 SDK to look or behave significantly differently on the beta vs the GM?

Betas being available doesn’t solve the problem because you can’t submit updates compiled using beta versions.

Right, but the point is you can use the beta to validate that your app, compiled with the old SDK, still functions normally on the new OS

I’m starting to see a pattern where it’s always the same apps that are broken on each major release. I suspect the developers of those apps are simply incompetent.

We only got the GM last night? how can anyone 100% know for sure their app is not going to break in some unexpected way between then and now? Thats the point of the grace period and the whole article / discussion here.

I’m talking about apps that have been broken since the first betas.

Those aren't the ones we're discussing here.

Perhaps, but updating their apps on a dime is simply unreasonable regardless.

Or they're always on the bleeding edge using the latest features.