To answer your question - it's because the major source of revenue for browser makers is search engines. Google, Yahoo, Bing etc. pay browser maker money to bundle their search engine in the browser, and also share a small percentage of revenue with them. Search engines make money from advertising. So obviously they discourage browser makers from including ad blocking tech in browsers. (Look at the money involved - Google Said to Pay Apple $15 Billion to Remain Default Search Engine on Safari in 2021 - https://gadgets.ndtv.com/apps/news/google-apple-default-sear... ... and you can understand why it is so difficult to say no to it).