One SCORE presenter said that the main reason for a website is to collect email addresses, ostensibly for follow-on email marketing. I'm sure the banner box/form is based on that perception.
This article showed up in my inbox: Hierarchy of Trust: The 5 Experiential Levels of Commitment and I recommend you at least skim over it.
The basic premise is that most websites ask too much of their visitors too quickly! I'm unsure where this pushy attitude comes from: Is this because the developers have the technical know-how and want to impress their clients? Is it because owners (who pay the developers) insist because they have seen it elsewhere?
If you're building a website, or having one built for you, this article should be required reading.
Here is a graphic from near the end of the article:
Here's the link again (it will open in a new tab or window):
Hierarchy of Trust: The 5 Experiential Levels of Commitment
I've been following Jacob Nielson's work at www.UseIt.com for over a decade, and he does have my email address for his periodic newsletters. I don't sign up for many publications, but this is one I'm glad I found! He's built a business on teaching website usability.