It's an easy fit for the information-focused sideprojects I've typically created, providing the content needed to rank with no additional effort, but it can work for any project creator willing to put a little effort into creating content about their project and promoting that content (to gain links to their domain). And most importantly, it keeps me focused on creating something people want, because I'm typically expanding the project in areas where I see there's a high volume of searches (through keyword research tools).
I think it really just comes down to where your potential customers may be hanging out / searching. For my side project, I've had decent success responding to posts/questions on sites like Quora, where someone is looking for exactly what you offer. It's free too (besides for your time!).
The book Traction (https://www.amazon.com/Traction-Startup-Achieve-Explosive-Cu...) gives a pretty solid overview of different marketing methods/strategies.