Google's algorithms continuously end up changing. Even if you're able to find some subtle way to game the system in the short-run, in the long-run your site has to have great content that people want to share with their friends. Depending only on Google for your business's success is a very risky game to play. You can get thousands of visitors from Google per day, and then wake up the next day and see that a new update to the search rankings makes it so that your page now has a few dozen visitors per day. That's why Facebook and all other social networks are still vital for any brand's success. You can find many new channels to distribute your message to the people that strongly care about it.
When we consider why people like pages on Facebook, it always comes down to them finding something that they value. Whether or not it's something funny that makes them laugh or perhaps something informative that makes them think - great content makes people remember your business and share it around to their friends. Advertising can certainly always help. You can go out there and use a ton of Facebook ads. Or you can go out there and buy Facebook likes until the cows come home, but if you don't have any desirable or interesting content on your site, you're never going to get any significant traction.
What is Good SEO?
Hiring high-priced SEO consultants can often be a waste of time. Many of them will recommend SEO strategies that quickly work and charge you dearly for it. They'll know of some automated tools to post lots of low quality links on new pages. Google will quickly see that and you'll have some initial traffic. They'll get as much cash as they can from you and make you think that they're flawlessly executing a grand vision. But a few months down the road, Google will see this and you'll be penalized. This is the wrong strategy to take. Good SEO starts with great developers who build a great platform, and then comes down to creating great content that people are actually excited about sharing.
This is why content marketing is the new SEO and why brands that care about their online presence don't ignore the possibilities available to them on social media. Smart brands do everything that they can to make sure that their content is shared on social media. And they do this by focusing really hard on creating the best possible content.