Is Wordpress.com the most expensive blogging platform out there?

This is not a link-bait, I am genuinely wondering. The link takes you to a simplified summary at my blog. I am curious what people think in general about this as this was not the case with Wordpress.com just a few years ago. The thought came to mind as I notice Tumblr's success and the failing of other blogging platforms (let's also not forget the merging of Microsoft's blogging space with Wordpress not too long ago).