Question:

Why does Google do the Google slap?

Answer:

Google wants a relevant "Message To Market Match"
Relevant search results for what people want

I call it the "chain of relevance":

1. Person searches on google for an answer to a problem
2. Person clicks on ad with a preconceived notion of what the landing page
will have.
3. The page title matches the search.
4. The landing page has the content that the person wants.

Google wants users to be happy when they come to your site. They want
people to find what they were looking for. If you try to trick the search
engines, you always have to play catch up and will eventually lose.

Google receives complaints from dissatisfied users and trys to change its
processes to make users happy; the slap is google’s best guess attempt at
the change.

Google suddenly realizes that long term success is based on a positive user
experience.