I think it's more that email is something I generally consider reasonably private. Of course I know that in reality all that is happening is that it is being parsed for certain keywords etc.
Whereas targeted advertising based on being on a particular public section of a public website feels much less intrusive.
I suppose it's like getting adverts on TV for items that are somewhat related to the show that you just watched vs getting letters through the mail advertising debt consolidation services because on the same day you also got mail from your bank telling you that your overdraft is maxed out and your credit card is overdue.
Whereas targeted advertising based on being on a particular public section of a public website feels much less intrusive.
I suppose it's like getting adverts on TV for items that are somewhat related to the show that you just watched vs getting letters through the mail advertising debt consolidation services because on the same day you also got mail from your bank telling you that your overdraft is maxed out and your credit card is overdue.