“Every link you put on a webpage in some way detracts attention from
every other link. A “landing page” is typically a page someone lands on
when they click on a keyword or banner ad. These pages generally have  a very specific purpose-to sell something, to get you to join something, etc.

its excellent report, Landing Page Handbook, Marketingsherpa found that
the more clinical, simple and focused a landing page is, the more
likely it is to succeed. Any links that do not support its primary
objectives will create leakage of potential customers, as they click on
‘interesting’ links that lead them away from the sale.”

This one above is from Mr McGovern. I haven’t read/seen the Sherpa book… it USD247, but the link is below if you’re interested

  Landing Page Handbook: How to Raise Conversions — Data & Design Guidelines