Direct Linking for Affiliates?

The biggest benefit - to capture their names and email before sending them off to the actual sales page. Sure, you won't get as many views on that sales page as you would if you do direct linking, but you'll also build up a list of serious people who are willing to give you their name and email for the information on the other side.

It's also more cost effective - you have a list of people you can sell to over and over again without paying more whereas direct linking from ads will cost you money every time you get someone to click - even if it's the same person!

And unless I'm mistaken, I believe you can't use affiliate links directly for FB ads.

No.

The purpose is to get folk to click your link and provide buying traffic to the product sales pages.

That's a totally different proposition.

The important point to appreciate is that it's different qualitatively, not just quantitatively (i.e. it isn't something that you can "make happen satisfactorily" just by "having more traffic in the first place").

"Whether your traffic becomes buying traffic depends on your interactions with it" (Marketing-101).

These might help you: this first post was written mostly about ClickBank, but it applies to plenty of other affiliate marketing, also. Read carefully: What are the best ways to promote click bank products?

If you want other threads to look at, to learn what's important and outcome-determining about affiliate marketing, here are three of them...

Is it a good idea to spend some time on building a mailing list ?

Without Building a List, How Consistent is Your Income from Affiliate Marketing

Does anyone even make money online without an email list?

I think the point you're missing is that people who "go straight there" almost never buy the first time they see the sales page, but if you don't collect their email address, there won't be a second and third and fourth and fifth time.

I have some affiliate-links on my websites, in every niche in which I do business, but the people who click on those links and buy the product are the ones who got to those links from a link in an email I sent them (having given me their email address at an earlier visit to the site).

Don't confuse "traffic" with "customers".

Good luck!