I went through the code, and it is roughly equivalent to doing it without classes. The nesting level in the example isn't deep - everything seems to be beneath a SnapStore or a SnapFormStore, without inheriting from user defined classes. I think the use of classes is fine, and the way that it's introduced in the blog post is good, it says "plain TypeScript classes". It is used as a means for ergonomically writing and understanding the code more than it is for setting up invariants or complex polymorphism.