When people click on an advertisement it is best practice to have them arrive on a dedicated landing page. This is because:

People expect to see a page that is all about the subject they clicked on. If I click on an advertisement for standing desks, I expect to land on a page dedicated to them , not general desks or even worse, general office equipment.

Don’t make them think!

If someone is confused or required to work to find their standing desk, there is a good chance they will just move on to the next website.

Every competitor in the World is only a click away.

Test different pages and offers

A dedicated page also allows you to provide tailored offers that you might be trailing

Track performance

A landing page also makes it easier to track how effective a campaign is without relying totally on your advertisers logs

You could also be split (a/b) testing different pages to establish the best offer/layout/descriptions etc

What does Google look for from SEO?