>"what it matters for me it's that in the last 10 years they've always been reliable (as in 100% reliable) and on point with their descriptions and ratings, no matter the destination (from a 2-star hotel in the middle of the Carpathian mountains to a 5-star hotel in Istanbul).

I would say you have been unusually lucky then. The practice of fake reviews from booking.com are pretty well documented[1][2]. And 5 star hotels are generally a pretty safe bet just about anywhere in the world, you pretty much know exactly what the experience will be. Accuracy of a 5 star hotel says very little about booking.com.

>"In other words they really do provide value, the same way as Ryanair provides value (it doesn't matter that everybody likes to hate on Ryanair, everybody is still flying with them)."

You mean like suddenly grounding 50 flights a day for the next six weeks and giving customers no shortage of grief:

http://www.independent.co.uk/travel/news-and-advice/ryanair-...

>"I also spend more than 5 minutes reading through the actual reviews before making a reservation ..."

That doesn't really mean much when the reviews are gamed does it?

[1] http://www.telegraph.co.uk/news/2016/07/06/bookingcom-invest...

[2] http://www.huffingtonpost.com/jonha-revesencio/the-truth-abo...