I only glanced at the article, but it also reminds me of Dataflow programming, incrementally updated materialized views, etc. (all the same concept at the end of the day, and yes, very similar to observables)
Specifically, the application of dataflow to GUIs, which was well-researched at Adobe by Sean Parent, Mat Marcus, et al in the early 2000s called the "Adam" and "Eve" languages. There's more work at TAMU & University of Turku (by Jaakko Jarvi) under the name "Espresso", or something like that.
Basically, the "scopes" become constraints, and they use a hierarchical constraint solver to propagate state changes to the GUI elements, real-time, using a declarative dataflow programming model.
> It's not dataflow! It's closely related, but it's not.
https://youtu.be/HB5TrK7A4pI?t=2071