Well you can get a VPS for $2.50/mo these days with half a gig of ram, more than enough to handle 5-15 simultaneous visitors on your average WordPress blog.
The WordPress software IS free. The WordPress.com service is not, as you pay for it by attaching their domain name to yours thereby providing them free advertising.
Also, there's nothing to stop you from hosting your personal blog on your personal internet connection. Even if you don't have a static IP there's ways to solve that.
Both Facebook and Twitter DID support RSS, both, for years.
Each corporation decided to eliminate RSS from their platform around 3 to 5 years ago, because they wanted complete control over the distribution of "their" content (OUR social lives).
It's difficult to discuss this subject without running into this gigantic elephant in the room which is that the behavior of corporate "social media" giants is exploitative, bordering on criminal, and absolutely contradicts the best interest of the public, our nation, the internet, and intelligent life. This has really served to spotlight some of the problems with free market capitalism.
Blogging predates all blogging services, platforms, and software. Blogging was invented by early web pioneers. The corporations followed in the Gold Rush of the 1990s dot-com bubble, and they've been trying to monetize our social lives ever since.
Nowadays, thanks to marketing machines and television talking heads, nobody has "websites" anymore, we have "blogs".