End-to-End Encryption (E2EE) is known for it's awesome privacy. Still, very few services are offered with E2EE. Users have to use unencrypted services, which threatens their privacy.
This threat model takes a closer look at E2EE adoption and aims to debunk all the reasons why vendors "cannot" implement E2EE.
See https://threat-modeling.net/e2ee-adoption-threat-model/ for a deployed version of the threat model.