I think it's a very good article. Even if you disagree with some of the individual points in it, the advice given are very concrete, pragmatic, and IMO tunable to the specifics of each project.

On state, in my current project, it is not statefulness that causes trouble, but when you need to synchronize two stateful systems. Every time there's bidirectional information flow, it's gonna be a headache. The solution is of course to maintain a single source of truth, but with UI application this is sometimes quite tricky.

Yes it’s total madness to synchronize and replicate complex state that logically belongs together. This is why microservices are such hot garbage. Well, how people tend to use them anyway.

Monotonic state is also better than mutable state. If you must distribute state, think ownership. Who owns it? Eg Theres nothing necessarily wrong with having state owned by eg a mobile client that can be adjusted by the user. Then you can sync it to the backend if you want, but they are only a reader/listener, and should never try to control it directly.