[Dr. Bobsky]

I don't think the argument about tracking people for ad revenue makes much sense given that their laptop sales numbers pale in comparison to their phone sales (and the groups tend to have a high overlap).

It might be that they want data of their own consumer group using the laptop to try to explore future features that reasonably add value to the computers or iphones they sell in the future. I doubt it. Siri makes sense (or some sense) on mobile devices, but when I am home and not going anywhere and do not need information speedily, I rightly or wrongly believe that i am more capable of judging the value of a search/search result.

I am more in favor of chucker's explanation that this is a vanity choice.