Removing Value Proposition from Registration Form

Are there any sources out there that shows the benefits in removing the value proposition from registration. I remember reading an article a while back about this, but can't remember the source.

I started noticing that most websites rely on the landing page to state out the value proposition and leave the registration forms to be as simple and straight forward as possible. Any real data or studies would be appreciated. Thanks in advance!

Just for context, I'm trying to convince a co-worker in simplifying the registration form for our company's website.