Is WordPress your own platform? What about when you host it on your own hardware? When you used a shared server or a virtual private host? When you use Wordpress.com? Is Tumblr? Is SquareSpace?
I have some thoughts.
I agree with the exhortation to "be your own platform," but the way I'd define that is more technical, legal, and political in nature. People posting extensively on Facebook, Twitter, or Medium are relying on the future goodwill and unknown business models of those sites that their words and images will persist in some form and in a form that the creator wants. That's impossible to know. I've written a few things on Medium (not paid) because I liked the experience of their writing tools, their statistics, and their reach. I think two of the three items I wrote became featured and had several thousand reads. It's a wonderful way to write and a wonderful place to post.
But it's not mine. It's theirs.
I can't control the URL. I can't embed. I have no idea about what their ultimate plans are. They could delete all non-owned/paid content in the future with no notice. They could rework the design and it would be ugly. My words' persistence, both in appearance and permanent location, are dependent on factors beyond my control.
I always argue that people should register a domain name and only work with services (and pay for the level of service needed) so that they can front their own domain in place of any platform domain. That ensures some persistence. I've migrated my personal blog out of a hosted blogging platform into my own across multiple revisions and then into Squarespace. I've managed through scripting and redirects to mostly keep URLs dating back to its earliest days from breaking. (There's a few-month period in 2001 that seems in bad shape that I may have to recover from the Internet Archive, though.)
So Tumblr, Squarespace, Wordpress.com, and the rest seem like reasonable choices to me if you BYOD. Otherwise, you're once again relying that a company will continue to exist in a form of your choosing, rather than its own. This is coupled with the ability to export one's posts. This will sound hilarious, but I migrated to Squarespace (version 6 platform) a few months ago from Movable Type 5. I had to export from Movable Type, import via Wordpress.com, and then export from Wordpress.com to a format that Squarespace 6 could read. It worked surprisingly well. Very surprisingly well. But it shows the danger of platform lock-in.
Squarespace 5 offered a third-party posting API that would allow local storage and composition and then posting. Version 6 did away with that, although I believe from working with Squarespace (which has sponsored my podcast), this wasn't intended as lock-in. Rather, the platform was a huge overhaul, and they're still working on it. Posts can be exported, but because platforms vary, it requires some work to relink and format if you've used any of Squarespace's custom and quite useful features.
It doesn't benefit them to lose customers who don't want to migrate from version 5 to 6, or who won't sign up because content is locked away. (Of course it can be scraped and re-created if need be, but that's a pile of work.)
I own a platform, The Magazine; it is purpose built because Marco didn't find one that suited. He didn't want to make it a platform-for-lease to others because it would have made him beholden to others' needs, rather than his own. I feel the same way. I enjoy producing the publication, but it's exceedingly difficult to create a generic method of serving all the forms, audiences, and app stores with a similar experience. Many are trying. I hope some succeed!
Corrections: This article originally stated the Medium and Squarespace (version 6) lack export. That's not the case. Both let you export your corpus: Medium as formatted HTML that matches their layout and Squarespace both as a WordPress-compatible export and on a per-post basis to grab JSON objects. The point with Medium (now made in the correction) is that they own the URL: the permanent persistent location that gets linked to. With Squarespace, the concern about lock in has more to do with its options that the system converts into standard HTML which have to be re-created elsewhere. Sorry for the errors. [GF]
[Image: Flickr user Kelly Sikkema]