When searching for an accomodation, booking.com offers a map, which shows the price of each accomodation, with filters applied. This is so useful and I wish other travel sites also had this.

A list of a 200 hotels of $50-100 is simply not enough information when searching in an unknown city. I need to narrow down that list, for example with features like a kitchenette (60 hotels left), but also a location near the city center, and not 20-30 minutes away in some suburb (20 hotels left). With booking.com I can now see on a map 20 pins of hotels with their pricing. Ok, some hotels are hostels with a Shared-6 room, which is one filter you cannot actually apply unfortunately (hey booking.com, if you are reading this, this is a hint!).

..then I know the hotel names, and search on the hotel's own site or other travel sites if there are any deals (genius dicounts sometimes help). Sometimes, Booking.com is cheapest, sometimes it is not.

I agree. Their website and mobile app as well seem to be of very high quality (though unfortunately it is not that hard to be exceptionally good in that compared to all the buggy software around us)

I have seen their presentation on a ML-related conference and what goes into which pictures they show for you for a given room is quite advanced. E.g. whether you will prefer a photo of a pool vs a nice room, etc.