yes, and also for advertising if amazon can start selling ads to you, based on what you're talking about, that would be much more desirable than ads based only

yes, and also for advertising if amazon can start selling ads to you, based on what you're talking about, that would be much more desirable than ads based only on viewing/purchasing history. messaging in particular is also a really viral phenomenon - you choose your app based on where your friends are and you don't switch. having a loyal captive audience is really useful to start selling to, a la wechat payments or other value add services where you can take some transaction fee. this fits very well with amazon's overarching business model of 'middlemanning every transaction'