Short answer: if you compare text links to presell pages you compare apples and oranges!

Pre-Sell Pages are not like simple text links!

Presell pages have an inherent value to both – users and search engines… and that can not just be devalued! Whatever algorithm Google claims to already have or to invent soon!

A good reason why pre-sell pages are becoming more and more popular!

While placement of text link ads is a single – let’s say old-school optimization method, pre sell pages are the Ferrari-method for increasing human traffic to your site the legit way!

Pre-Sell Pages are good for the user ! and that means, they are good for your rankings !

original quote of Google Engineers:

What’s good for the user is good for your site’s ranking

That’s another great reason why pre-sell pages are so valuable.

You need content on old, trusted and established sites writing about you and link to you!
That is just so different from placing single (hopefully at least relevant) text links of a few characters on another site. It’s about contributing content and value to other site’s and the user.

And that is the reason why it is so much better to pay eg $ 400 for a GREAT presell page on an authority site having 5 links to you instead of getting 5 separate links for $ 80 … This is true for Google today – and other search engines will follow.