I agree. Last time I looked at why they were designing it be Chrome-only, it appeared to be due to a reliance on Google Cloud Messaging (GCM, [1]). This could be due to one or both of the following factors:
a) they wanted to re-use as easily as possible their existing back-end infrastructure which already uses GCM for the Android app.
b) they are using GCM to ensure that their desktops users are also "screened" by Google's existing authentication/security infrastructure - which ties a user down to a phone number among other things.
a) they wanted to re-use as easily as possible their existing back-end infrastructure which already uses GCM for the Android app.
b) they are using GCM to ensure that their desktops users are also "screened" by Google's existing authentication/security infrastructure - which ties a user down to a phone number among other things.
[1] https://developers.google.com/cloud-messaging/
Edit: clarity, typos