> A lot of comments here are blaming the user for using the same username/password on multiple sites, allowing their account to be compromised. This is missing

> A lot of comments here are blaming the user for using the same username/password on multiple sites, allowing their account to be compromised. This is missing the point. Omitting the lack of 2FA is missing an even more important point because it's cases like this why 2FA is pretty much mandatory today. But instead of using already available solutions, you want to reinvent the wheel with "a pairing procedure". Gee, that sounds awfully familiar to what 2FA does, which also would have completely eliminated this failure mode, if the user would have bothered to actually use it. In that context, I really don't see what Google could do differently with Nest. If users don't use additional security, then you can add all the additional security you want.