Facebook in the age of promoters having very little money to actually promote anything is pretty indispensable, as you can see what works, what doesn't and target your marketing efforts accordingly. And you can make do with very small amounts of money (if you're realistic with your expectations). Of course targeted marketing in other social media channels is also well possible & worth doing, but I don't think anything's quite as ubiquitous as FB.
Of course, "liking each others pages" is, well, a circle jerk. Just having a bunch of likes doesn't mean anything as such, it's what you do and how you interact with the audience you've built.