Hi and welcome to the forum. Gosh, this is an ancient thread but it's an interesting subject to raise again because almost everything has changed since the previous discussions.
Facebook was founded in 2004, but not open to the public until 2006. At the time we were discussing this before it was still relatively insignificant for the average person on the web. Now, of course, it's everywhere and so any study of SEM or SEO would need to include an understanding of marketing on Facebook.
(Read the history of Facebook here:
https://en.wikipedia.org/wiki/Facebook )
Amazon's growth has also had a huge influence - and it's also a major search engine, which I think some people might not realise.
There are lots of books and courses about SEO and SEM, but many of them are written by MMOers (people who make money by "teaching" people how to make money online - even if they don't know how to themselves, other than by selling MMO courses).
Possibly the best place to look for worthwhile courses would be Coursera, which offers high quality free courses on many subjects including marketing. (I would not recommend the likes of Udemy for any online business subject.) There are also a few respected websites (and a lot which aren't so good) with a focus on these subjects but their names aren't at the top of my head because I've not been paying so much attention to this part of online business recently.