Comment Data mining by telcos (Score 3, Insightful) 108
Judging from the comments, quite a few of you are skeptical about the usefulness. I have a different perspective based on my work experience.
I used to work for a large telco in the APAC region (100s millions of users in multiple countries) where I was part of the team that developed a system to mine as much data as possible from users: location data (triangulation), call records, web data. From this data individual profiles were created which were then (only) sold in an aggregated/anonymized way (things might have changed of course). The tools we developed were licensed to telcos all over the world.
Analyzing DNS requests was definitely part of the arsenal of tools used for HTTPS requests (other techniques are connecting to the server and analyzing the certificate presented).
In my opinion, Firefox's DNS over HTTPS will at least partially help against this type of unwarranted snooping by telcos.