Firefox 41 will use less memory when running AdBlock Plus 11 years ago
What doesn't prevent these vendors to advertise their own products. Or make money by letting others pay. Apple, MS and {{any_big_company}} do everything that generates revenue. Even Mozilla has started to sell data and advertising space in Firefox. I don't care where the spam is coming from. And no Mozilla, I will certainly never book my next holiday trip on booking.com.