Using the sign-up email addresses, Disney could link people or households across platforms and properties.
This article states that though Disney+ is an ad-free streaming service, Disney as a parent company is partially ad-supported. Through Disney+, Disney can work towards unifying its ad sales organisation as the streaming service brings with it data which can be used for ad sales across Disney’s TV networks, sites, apps and ad-supported streaming services.
Historically, Disney hasn’t had direct relationships with its audience. But with Disney+, it can gather users’ email addresses. Typically, Disney doesn’t work in silos.
It makes movies, promotes them on its TV networks and converts them into amusement park rides where it sells merchandise. Establishing direct relationships with audiences brings in data using which Disney could deploy strategies combining its linear TV and digital ad inventory to serve campaigns across platforms.
[2 minute read; article may be behind a paywall]