I think the main problem is that Chromium still contributes towards the browser engine monoculture, as it is bug-for-bug compatible with Chrome. Therefore if you switch to Chromium, it’s still enough for the web sites to test for Chrome compatibility, which they will, because it has the largest market share. Users of competing browsers suffer, further driving the lure of Chrome (or Chromium).
On the other hand, if people switched to some other engine, one that does not share the same core engine or even the same history, this will no longer hold: web sites would need to be developed against the spec, or at least against all the browsers they might realistically expect their customers to use.
Then there are the cases where you want the LLM to actually interact with the page, using the current web page state and your credentials.
For example, one might want to tell it to uncheck all the “opt in” checkboxes in the page… And express this task in plain English language.
Many useful interactive agent tasks could be achieved with this. The chatbot would be merely the first step.