>>/48571/
> yandex browser add-on that sends visiting URL
Should have list this. People install bunch of addons to their browsers. Some do a bit more than advertised.
> Now it is even easier...
I concur.
> There is nothing that prevents search engine from publishing everything it knows.
Yes, upstairs they can decide to change the behaviour of their service any time.
But I meant the other way around. From the viewpoint of someone who wants his site to be displayed among the search results, this sucks. Imagine one has several sites, even if all linked on each other, and it's 100% sure if one gets indexed, the rest will do too, they won't appear in any search until manually registering them with Google.
Not sure how others work. Bing, DDG. Searx I think aggregates others (and even DDG relies on something else).