As someone who has tried almost all of the AI browsers that are accessible or in a relatively open beta, plus all the browser control frameworks and agents, I super agree with the notions behind this post.
Curious about your approach, though: so, it's a literal script, or an LLM being told to follow a deterministic script and only get subjective when necessary? Based on the blog, it looks like the former, but why not the later? Get the LLM to be pseudo-deterministic but still step-by-step it so that it can handle UI changes and adjacent interfaces.