SAN JOSE, June 29 -- For years, the Netflix household worked like a shared folder: one account, one password, up to five named slots for whoever claimed them. Switching profiles was frictionless - tap a name, start watching. That dynamic quietly changed on June 15, when Netflix began rolling out a requirement that every adult profile be linked to its own unique email address.

The in-app prompts arrived without warning and, in most cases, without a skip button. An email tied to a profile that doesn't have one yet. A new one-time passcode login flow for whoever claims it. Individual settings - language, audio, subtitles - that now belong to a specific person rather than a shared slot. Netflix frames the change as a security and personaliza...