Every year Google changes the way it's search engine acts. They can tweak settings here and there, and add new algorithms over 500 times a year. Many of the changes will be minor and barely noticeable, however some can be very major and can completely disrupt whole industries.
Gone are the days of where you could stuff the header of your site with keywords, these days it's all about content, social media influence, link backs...etc. It's all about making your site better for the person coming to it. Creating relevant information, instead of making irrelevant titles to produce traffic.
If you're into web development and web design, SEO is one of the biggest and most important things you could learn. And SEO optimisation does work, trust me, I've optimised UltraLinx as much as possible where I can and because of this I've been able to produce lots of traffic, new readers and have keywords leading to my site. Search is my biggest traffic driver.