Communicating with your market, i.e. readers in your genre, still works. However, it's not a magic bullet and it takes work. Also, communicate as a reader/fan of the genre first. If you're only there to sell your book, people will notice.
I have an active and long-running (since 2010) blog. I announce my books there, but the vast majority of what I post are not "Hey, I have a new book out" posts, but episode by episode reviews of genre TV shows and movies, reviews of books and stories, usually older, convention reports, general genre discussions, interviews with other creators, links round-ups, new release round-ups, etc... Once per month, I post a short story for free. I also comment on other blogs, do podcast appearances, guest posts and have a regular gig at a popular group blog. The idea is to become a known and trusted voice in the community.
Not all blog readers go on to buy my books, but quite a few of them do. Besides, my blog and the posts I write for other blogs and zines were popular enough to gain me two Hugo nominations for best fan writer. And that is a definite marketing advantage, because I can now put "The new book by two-time Hugo finalist Cora Buhlert" on every SFF book I publish (also on non-SFF books, but mystery or romance readers don't care). Also, it builds connections. One of my fellow finalists runs a popular genre newsletter with a promo section. When I ask him to feature one of my books, it had an impact.
I'm active on Twitter, but mainly to be social and interact with people who share my interests. And yes, they buy books, too. When I have a new book out or a cover to show off, I of course tweet about it. And if I have a book that matches some current season or trend, I also mention it, e.g. "Looking for spooky reads for Halloween. Check out this bundle of my horror stories." As long as your Tweets are not "Buy my book" all the time, no one minds.
Another good venue I've recently found is Discord. Discord has dedicated groups for all sorts of topics and genres. I recently joined a group for a niche subgenre (sword and sorcery) with a hungry, but underserved readership. Most of the time, I just chat about books, films, TV shows, etc..., but when I have a new book out, I mention it. And I promptly get sales.
So in short, it can be done, but it's not an easy or straightforward process and you have to be genuinely interested in the genre you write, so you can discuss it intelligently.