Also to add to what you said, switch away from (Google) Chrome everyone!!

Imagine this message, but on every website, and it literally cannot be prevented, as the browser itself will sooner than later just straight up tell the sites "yo, your content has been modified, maybe block the user from viewing", snitching on you.

Come to think of it now, I wonder if this will affect poorly implemented sites using that feature to accidentally (or intentionally…) disable dark mode/reader extensions.

And then, due to Chrome's market share, if left unchanged, web developers/companies will at some point just not bother anymore. Imagine "this works best in Google Chrome, download now" you see for some web apps today, but even with the most basic text based site that can't prevent you from using your Adblocker in e.g. Firefox or Safari.